Engineering Standard Rolling Stock CRN RS 011 ROLLING STOCK WHEEL DEFECT LIMITS Version 2.0 Issued October, 2016 Engineering Standard Owner: Approved by: Authorised by: Principal Engineer Rolling Stock and Plant Bryan Turnbull James Zeaiter Disclaimer. This document was prepared for use on the CRN Network only. John Holland Rail Pty Ltd makes no warranties, express or implied, that compliance with the contents of this document shall be sufficient to ensure safe systems or work or operation. It is the document user s sole responsibility to ensure that the copy of the document it is viewing is the current version of the document as in use by JHR. JHR accepts no liability whatsoever in relation to the use of this document by any party, and JHR excludes any liability which arises in any manner by the use of this document. Copyright. The information in this document is protected by Copyright and no part of this document may be reproduced, altered, stored or transmitted by any person without the prior consent of JHG. UNCONTROLLED WHEN PRINTED Page 1 of 37
Document control Revision Date of Approval Summary of change 1.0 17/4/12 Adapted from RailCorp Standard ESR 0330 2.0 5/10/16 Reviewed for relevance and currency Summary of changes from previous version Section 6.2 Photographs added to figure 21 Summary of change JHR UNCONTROLLED WHEN PRINTED Page 2 of 37
Contents 1 Scope... 4 2 Wheel rim thickness... 4 3 Permissible variation in wheel diameter... 5 4 Wheel defects... 5 4.1 Thermal cracks... 5 4.2 Damaged or fractured wheels... 10 4.3 Spalling or shelled tread... 13 4.4 Skidded wheels (wheel flats)... 17 4.5 Scaled wheels... 21 4.6 Arrises... 24 4.7 Steep flanges... 27 4.8 High flanges... 28 4.9 Hollow tread... 29 4.10 Thin flanges... 30 4.11 Short flange... 31 4.12 Misaligned brake gear... 32 5 Weld repairs of wheel skids... 34 6 Wheel tread profile re-machining... 34 6.1 Surface finish... 34 6.2 Witness marks... 34 6.3 Machining Tolerance... 35 7 Examination of tyred wheels in service... 35 8 Overheated wheels... 36 9 Wheel gauges... 36 JHR UNCONTROLLED WHEN PRINTED Page 3 of 37
1 Scope This standard describes the minimum allowable conditions under which integral steel wheels and tyred wheels may continue in service, and operating restrictions imposed for defective wheels found in service. 2 Wheel rim thickness A rail vehicle shall not remain in service if it has a wheel rim thickness less than the limits specified below, with reference to Figure 1 - Freight vehicles up to 25 tonne axle load 20 mm - Freight vehicles over 25 tonne axle load 22 mm - Passenger vehicles 25 mm - Locomotives 22 mm (See Note below) NOTE: Locomotive wheel rim thickness may be dictated by bogie component clearances, such as gearboxes, above the rolling stock outline Flange Thickness Tread Centre Flange Angle Flange Height Rim Thickness 70 mm Rim Width Wheel Web or Plate Tread Diameter Hub Diameter Bore Diameter Figure 1 Typical Wheel dimensions JHR UNCONTROLLED WHEN PRINTED Page 4 of 37
3 Permissible variation in wheel diameter The maximum wheel diameter variation on freight vehicle wheelsets, bogies, and between bogies fitted to the same vehicle/deck shall be as per the limits specified below: - Wheel tread diameter per axle (new or re-turned) 0.5mm - Wheel tread diameter per axle (in service) 1mm - Wheel tread diameter per bogie 25mm - Wheel tread diameter per vehicle 60mm The maximum wheel diameter variation on locomotives, locomotive hauled passenger cars and multiple unit rolling stock shall be in accordance with vehicle manufacturer s requirements, but they shall not exceed the values specified above. 4 Wheel defects This specification details the allowable limits for the inspection of all rail vehicle wheels for various tread and flange defects. The text outlines the action to be taken when defects are detected. Allowable speeds specified below are not to exceed the prevailing track speed limit. The accompanying series of instructions and associated diagrams are included to indicate degrees of severity of wheel tread damage likely to be found and the appropriate action to be taken in each case. 4.1 Thermal cracks Thermal cracks are the result of alternate heating and cooling of the wheel tread and rim area, and are the most severe form of wheel defect. Heating due to the friction from brake blocks during frequent braking produces a network of fine, shallow, superficial lines or "checks" running in many different directions on the wheel tread surface. Because of its similarity to the type of fine cracks found in pottery glaze, it is sometimes referred to as surface crazing. This type of cracking should not be confused with true thermal cracking, and if found on its own causes no problems. Thermal cracks are usually transverse, across the wheel tread and are caused by excessive heating or hot spots on the wheel tread from brake block friction, followed by rapid cooling. Crack growth initially is due to the heating and cycles from heavy braking. If allowed to propagate (grow) without corrective action, thermal cracks can develop to the point where the wheel will fracture. Thermal cracks have been shown to be more prevalent in AAR B grade wheel material in combination with medium friction brake blocks. This is because the brake block material is hard and does not conform readily to the wheel shape resulting localised pressure points causing hot spots on the wheel tread. Overhanging brake blocks create a hot band on the edge of the wheel tread and thus can contribute to higher risk edge thermal cracks. Many shallow thermal cracks can be removed by machining but extra care must be used to ensure that the crack has been completely eliminated in the machining operation. If thermal cracks are found on a wheel, then the vehicle's brake system should be first checked for evidence of brake malfunction causing dragging brakes (sticking brakes). JHR UNCONTROLLED WHEN PRINTED Page 5 of 37
Important: If there is the slightest doubt as to the severity of the thermal crack, always report the higher classification. (For example, if the defect description falls between a class 2 and 3 thermal crack, then a class 3 thermal crack would be reported). 4.1.1 Class 1 thermal cracks Any thermal crack/s up to 10 mm long detected on the tread surface within the zone shown in Figure 2 but not on or extending onto the rim face of the wheel is acceptable. (see Clause 4.1.4). 30 mm 12 mm Figure 2 - Class 1 thermal crack zone No action required 4.1.2 Class 2 thermal cracks Any thermal crack/s between 10 mm and 30 mm long, identified in the zone shown in Figure 3 requires attention. See the required action below. Thermal cracks between 10 mm and 30 mm long in the shaded zone 30 mm 12 mm Figure 3 - Class 2 thermal crack zone Locomotives and all passenger vehicles: Relevant vehicle must have wheel inspection details recorded by the Operator to ensure that the wheel condition is identified as soon as it progresses to a class 3 thermal crack. Freight vehicles: The examining person shall re-examine the relevant wheel/s during programmed vehicle examination/inspection and maintenance. No other action is required for class 2 thermal cracks. JHR UNCONTROLLED WHEN PRINTED Page 6 of 37
Rail-bound infrastructure maintenance vehicles: Relevant vehicle must have wheel inspection details recorded by the Operator to ensure that the wheel condition is identified as soon as it progresses to a class 3 thermal crack. RESTRICTION: No speed restriction is required for a vehicle with class 2 thermal cracks. Photograph 1 An example of Class 2 thermal cracks 4.1.3 Class 3 thermal cracks Any thermal crack/s over 30 mm and up to 40 mm long, identified in the zone shown in Figure 4 requires attention. See the required action below. Thermal cracks between 30 mm and 40 mm long in the shaded zone 30 mm 12 mm Figure 4 - Class 3 thermal crack zone NOTE: Any vehicle found with a class 3 thermal crack which has the wheel approaching the condemning diameter (i.e. less than 6 mm left on the tread above the condemning dimension), must be treated as if it had a class 4 defect. JHR UNCONTROLLED WHEN PRINTED Page 7 of 37
CRN Engineering Standard CRN RS 011 Locomotives and hauled passenger vehicles: The relevant vehicle must be scheduled for wheel turning within 14 days of detection. Diesel multiple unit vehicles: The relevant vehicle must be scheduled for wheel turning within 14 days of detection. Freight vehicles: The relevant vehicle must be worked out of service for repairs. Rail-bound infrastructure maintenance vehicles: The relevant vehicle must be scheduled for wheel turning within 14 days of detection. RESTRICTION: No speed restriction is required for a vehicle with class 3 thermal cracks. Photograph 2 Example of Class 3 thermal cracks JHR Issued October, 2016 UNCONTROLLED WHEN PRINTED Page 8 of 37 Version 2.0
CRN Engineering Standard 4.1.4 CRN RS 011 Class 4 thermal cracks Any thermal crack greater than 10 mm long, identified in the shaded zone at the wheel tread outer edge or any visible thermal crack on the flange shaded zone, as shown in Figure 5 OR A thermal crack greater than 40 mm long anywhere on the wheel tread, requires attention. See the required action below. Any visible crack within the shaded flange area Cracks longer than 40 mm anywhere on the wheel tread Cracks longer than 10 mm within the shaded edge area 12 mm 30 mm Figure 5 - Class 4 thermal crack zone Photograph 3 Example of Class 4 thermal cracks NOTE: Class 4 thermal cracks are a serious defect which can result from extended heavy braking or periods of abnormal braking. For instance, in the case of overhanging brake blocks, JHR Issued October, 2016 UNCONTROLLED WHEN PRINTED Page 9 of 37 Version 2.0
if there is any evidence of a crack on the outer edge of the wheel tread or extending onto the rim face, then this condition shall be considered a class 4 defect. All vehicles: Under no circumstances must a wheel with a Class 4 crack be allowed to enter service if found at a pre-trip examination or at a depot. RESTRICTION: Locomotive, as a part of a train: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed but at not more than 40 km/h, provided the use of automatic or independent brake on the relevant locomotive is kept to an absolute minimum. Light locomotive: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed but not more than 40 km/h, using dynamic brake, if available, and provided the use of automatic or independent brake is kept to an absolute minimum Hauled passenger vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed but at not more than 40 km/h, provided the relevant brakes can be isolated. Diesel multiple unit vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed but at not more than 40 km/h provided the relevant brakes can be isolated. Freight vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed but at not more than 40 km/h provided the relevant brakes are isolated. Rail-bound infrastructure maintenance vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed but at not more than 40 km/h provided the relevant brakes can be isolated and/or the use of wheel tread brakes can be kept to an absolute minimum. NOTE: If these restrictions unduly affect vehicle/train operations, the vehicle/train must be immediately removed from service to the nearest available siding. The relevant vehicle may then be repaired (bogie/wheelset change) at that location. 4.2 Damaged or fractured wheels 4.2.1 Fatigue cracks Fatigue cracks generally originate from a defect in the wheel. These defects can be caused by either external damage or a manufacturing defect. 4.2.2 Manufacturing defects This type of defect generally occurs on the wheel web and can result in a fatigue crack which propagates circumferentially around the web. In other cases, defects have led to large pieces of the flange falling off in service. JHR UNCONTROLLED WHEN PRINTED Page 10 of 37
W37 type freight wheels originating in New South Wales, (these are fitted with 18R or 9R axleboxes), are particularly prone to manufacturing defects and should be specifically examined for cracks. Although this type of wheel has essentially been phased out of service, some wheels may still be in service. Any crack originating from a manufacturing defect shall be classified as a class 4 or greater defect (see clause 4.2.4). 4.2.3 External wheel damage This type of damage generally occurs as the result of a heavy impact on the wheel and may show up as a chip or gouge in the wheel flange or a bruise on the wheel tread. A fatigue crack can start at this defect and propagate quickly through the entire wheel. A close visual examination must be made of both flange surfaces and the wheel tread in order to detect the presence of any damage. Any chip or gouge in a wheel which is more than 25 mm long and/or 12 mm wide shall be classified as a class 4 defect (see section 4.2.4). 4.2.4 Class 4 - Fatigue crack, manufacturing defect, external wheel damage All Vehicles: Under no circumstances shall a wheel with a class 4 defect be allowed to enter service if found at a pre-trip examination or at a depot. RESTRICTIONS: The same restrictions to those applicable for Class 4 thermal cracks, shall apply. If these restrictions unduly affect vehicle/train operations, the vehicle/train must be immediately removed from service to the nearest available siding. The relevant vehicle may then be repaired (bogie/wheelset change) at that location. 4.2.5 Class 5 - Fractured wheel Any crack running through the rim, web or boss of the wheel must be classified as a class 5 defect. A fractured wheel may be the result of either a thermal crack or a fatigue crack which has propagated or grown. The vehicle shall not be moved until the damage has been examined and assessed by a suitably qualified person. After examination, the vehicle may be allowed to clear the section to the nearest siding at a safe speed as nominated by the qualified person. Once the vehicle is in a siding, it shall not be moved further until: - a pony bogie has been fitted; Refer to Clause 4.2.5.1 OR - a wheelset/bogie has been changed. Once a vehicle has had a wheelset/bogie change, it may be returned to service. JHR UNCONTROLLED WHEN PRINTED Page 11 of 37
Photograph 4 Example of Class 5 fatigue cracked wheel 4.2.5.1 Working with pony bogies Once a vehicle is fitted with a pony bogie the vehicle shall be transferred to the nearest depot as follows: - Defective locomotives, or loaded freight vehicles, supported by pony bogies must be accompanied by a suitably trained mechanical maintenance person, who shall take every opportunity to examine the pony bogie assembly and bearings whilst the vehicle is in transit. - The speed for locomotives and loaded freight vehicles when mounted on pony bogies shall not exceed 15 km/h, reduced to 8 km/h over points and crossings. - Empty freight and empty passenger type vehicles supported by pony bogies are permitted to travel unaccompanied at a maximum speed not exceeding 20 km/h, reduced to 10 km/h over points and crossings. JHR UNCONTROLLED WHEN PRINTED Page 12 of 37
4.3 Spalling or shelled tread Spalling or shelled tread occurs when pieces of metal break out of the tread surface in several places more or less continuously around the tread circumference. This defect can result from thermal damage, skidding or over-stressing at the wheel-rail contact point. It is usually attributed to a combination of two or more of the following factors: poor track and excessive speed resulting in high impact stresses, excessive vertical loads, excessive braking (thermal damage and/or skidding) or the use of wheels without tread braking, such as those used in conjunction with disc brakes. Spalls can range in size depending on the age and depth of the defect. Their frequency can be such that the entire tread circumference is covered with craters to the extent that they become joined. Wheel tread condition, particularly spalling, has a pronounced effect on wheel and brake block life. For example, brake block wear is approximately 1.5mm per 1000km travelled with new wheels and extreme spalling can increase this rate to approximately 20mm per 1000 km. Pitting is the presence of very small marks on the tread. It can be the initial stages of spalling but is not in itself a concern. NOTE: If there is the slightest doubt as to the severity of spalling, always report the higher classification. Photograph 5 Example of Class 1 spalling on the wheel tread JHR UNCONTROLLED WHEN PRINTED Page 13 of 37
4.3.1 Class 1 spalling The wheel tread is mostly smooth with minor visible flaws or a blotchy appearance. Pitting may also be noticed. Areas of spalling up to 12 mm diameter may be scattered on up to 10% of the total tread area. No action required. However, Trim Blocks or cast iron brake blocks may be used to dress the wheel tread surface. 4.3.2 Class 2 spalling The spalling has progressed such that the spalls are up to 25 mm diameter. The total coverage may be up to 20% of the total tread area and the edges of the spalls may be sharp and jagged. Photograph 6 Example of Class 2 spalling on the wheel tread Locomotives: Wheels must have inspection details recorded to ensure that the wheel condition is identified as soon as it progresses to class 3 spalling. All passenger vehicles: Wheels must have inspection details recorded ensure that the wheel condition is identified as soon as it progresses to class 3 spalling. JHR UNCONTROLLED WHEN PRINTED Page 14 of 37
Freight vehicles: If any class 2 spalls are found, the examining person shall re-examine the wheel during programmed vehicle examination/inspection or maintenance. No other action is required for class 2 spalling. Rail-bound infrastructure maintenance vehicles: Wheels must have inspection details recorded to ensure that the wheel condition is identified as soon as it progresses to class 3 spalling. RESTRICTIONS: No speed restriction for any vehicle with class 2 spalling. However, Trim Blocks or cast iron brake blocks may be used to dress the wheel tread surface. 4.3.3 Class 3 spalling The spalling has progressed such that the spalled areas are larger than 25 mm diameter. These spalls may cover up to 50% of the total tread area and will be sharp edged and jagged. Photograph 7 Example of Class 3 spalling on the wheel tread Locomotives: Vehicles must have inspection details recorded by inspection personnel and be scheduled for wheel turning within 14 days of detection. All passenger vehicles: Vehicles must have inspection details recorded by inspection personnel and be scheduled for wheel turning within 14 days of detection. JHR UNCONTROLLED WHEN PRINTED Page 15 of 37
Freight vehicles: Vehicles must be worked out of service for repairs. Rail-bound infrastructure maintenance vehicles: Vehicles must have inspection details recorded by inspection personnel and be scheduled for wheel turning within 14 days of detection. RESTRICTIONS: No speed restriction for any vehicle with class 3 spalling. 4.3.4 Class 4 spalling The spalling is extensive for greater than 50% of wheel tread surface area or large spall areas 3 mm or more, in depth. Spalling of any size on wheel flanges is a class 4 defect. Any circular cracks associated with the early stages of spalling are also a class 4 defect. Photograph 8 Example of Class 4 spalling on the wheel tread JHR UNCONTROLLED WHEN PRINTED Page 16 of 37
All Vehicles: Under no circumstances must a wheel with this defect be allowed to enter service if found at a pre-trip examination or at a depot. RESTRICTION: The same restrictions to those applicable for Class 4 thermal cracks, shall apply. If these restrictions unduly affect vehicle/train operations, the vehicle/train must be immediately removed from service to the nearest available siding. The relevant vehicle may then be repaired (bogie/wheelset change) at that location. Bogies which have had wheels in this condition shall have their running gear thoroughly examined for evidence of loose or adrift components particularly in the axlebox and traction motor areas. Bearings shall be rumble tested and visually inspected with the removal of the front cover or gas plug, where applicable. 4.4 Skidded wheels (wheel flats) Wheel skids occur when a wheelst "locks up" due to sticking brakes, seized axlebox or traction motor drive, while the vehicle is moving. All skids eventually lead to further wheel damage such as spalling and therefore reduce the life of bogie unsprung components, such as bearings, traction motors, etc. Impact forces produced by a wheel flat are also detrimental to the rail and track structure. NOTE: If there is the slightest doubt as to the severity of a wheel flat, always report the higher classification. Wheel flats may be ground at the ends to reduce the severity to the next lowest category. A single car air brake test must be carried out on vehicles with skidded (flat) wheels, unless there is another obvious cause. 4.4.1 Class 1 skidded wheels The class 1 skid is a single wheel flat with a length of less than 25 mm. No action is required. However, Trim Blocks or cast iron brake blocks may be used to dress the wheel tread surface. 4.4.2 Class 2 skidded wheels The class 2 skid is a single wheel flat with a length between 25 mm and 40 mm or there are multiple class 1 skids Locomotives: All wheels with class 2 skids must have inspection details recorded to ensure that the wheel condition is identified as soon as it progresses to a class 3 skid. Passenger vehicles: All wheels with class 2 skids must have inspection details recorded to ensure that the wheel condition is identified as soon as it progresses to a class 3 skid. Freight vehicles: If any class 2 skids are found, the examining person shall re-examine the wheel during programmed vehicle examination/inspection or maintenance. JHR UNCONTROLLED WHEN PRINTED Page 17 of 37
Rail-bound infrastructure maintenance vehicles: All wheels with class 2 skids must have inspection details recorded to ensure that the wheel condition is identified as soon as it progresses to a class 3 skid. RESTRICTION: A speed restriction of 80 km/h must be placed on any vehicle with class 2 skids. Trim Blocks or cast iron brake blocks may be used to dress the wheel tread surface in an effort to reduce the skid to a lesser class. 4.4.3 Class 3 skidded wheels The class 3 skid is a single wheel flat with a length between 40 mm and 60 mm, or there are multiple class 2 skids. Photograph 9 - Example of a Class 3 Skidded Wheel (Multiple Class 2 Skids) Locomotives: Wheels with class 3 skids must have inspection details recorded and be scheduled for wheel re-machining. Passenger vehicles: Wheels with class 3 skids must have inspection details recorded and be scheduled for wheel re-machining. JHR UNCONTROLLED WHEN PRINTED Page 18 of 37
Freight vehicles: Vehicles having wheels with class 3 skids must be worked out of service for wheelset replacement. Rail-bound infrastructure maintenance vehicles: Wheels with class 3 skids must have inspection details recorded and be scheduled for wheel re-machining. RESTRICTION: All Vehicles: A speed restriction of 40 km/h must be placed on any vehicle with class 3 skids 4.4.4 Class 4 skidded wheels The class 4 skid is a single wheel flat with length between 60 mm and 100 mm or there are multiple class 3 skids. Photograph 10 - Example of a Class 4 Skidded Wheel All Vehicles: Under no circumstances must a wheel with a Class 4 crack be allowed to enter service if found at a pre-trip examination or at a depot. JHR UNCONTROLLED WHEN PRINTED Page 19 of 37
Locomotives: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed provided the use of independent brake can be kept to an absolute minimum Passenger vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed provided the brakes on the relevant vehicle are isolated. Freight vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a speed provided the brakes on the relevant vehicle are isolated. Rail-bound infrastructure maintenance vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed provided the relevant brakes can be isolated and/or the use of wheel tread brakes can be kept to an absolute minimum. RESTRICTION: All vehicle movements shall be at a safe speed not exceeding 25 km/h. If these restrictions unduly affect vehicle/train operations, the vehicle/train must be immediately removed from service to the nearest available siding. The relevant vehicle may then be repaired (bogie/wheelset change) at that location. 4.4.5 Class 5 skidded wheels The class 5 skid is a single wheel flat with greater than 100 mm in length or there are multiple class 4 skids. Photograph 11 - Example of a Class 5 Skidded Wheel JHR UNCONTROLLED WHEN PRINTED Page 20 of 37
All Vehicles: Vehicle with class 5 skids shall not be moved once detected until the tread surface defect is adequately rectified or a pony bogie has been fitted. Defect repair may be achieved by in-situ welding and build up of the tread defect area followed by grinding to restore a uniform profile. After rectifying the defect in the section, ensure that the vehicle movement is to the nearest siding at a safe speed which the attending mechanical maintenance officer nominates. Once the vehicle is in the siding, it shall not be further moved until: the wheel profile has been completely restored; or a wheelset/bogie change. If a pony bogie is fitted, the vehicle shall be transferred to the nearest wheel lathe in accordance with Clause 4.2.5.1. Upon reaching the wheel lathe the defective wheel, if weld repaired, shall be re-profiled to ensure all weld metal and the heat affected zone is removed. In practice this can be achieved by machining the wheel such that the radius is reduced by an amount no less than the skid length divided by eight (8). Bogies which have had wheels in this condition shall have their running gear thoroughly examined for evidence of loose or adrift components particularly in the axlebox and traction motor areas. Bearings shall be rumble tested and visually inspected with the removal of the front cover or gas plug. The vehicle brake system shall also be tested for correct operation and sensitivity. 4.5 Scaled wheels Scaling is the build up of metallic material on the surface of the wheel tread. It is usually attributed to sticking brakes which creates friction heat between the brake block and the wheel tread thus heating it to the stage where the material becomes molten and is buttered around the tread perimeter by the brake block/s. The molten metal eventually cools and forms thin layers of razor sharp scales.giving the tread a scaly appearance. Scaling may cover the entire wheel surface or any part of it. The method used to determine the severity of any given scaling is to measure its height from the normal wheel surface. As wheel scale is created by a brake malfunction, a single car air test is mandatory to determine the root cause. Important: If there is the slightest doubt as to the severity of wheel scaling, always report the higher classification. NOTE: For the purposes of interpretation of this standard, Classes 1 and 2 scaled wheel classifications are not relevant. 4.5.1 Class 3 scaled wheels Wheels with Class 3 scale have a very light surface smearing of scale present. Scale height is too small to measure with a standard rule (less than 1 mm). This smearing effect is usually caused by the brake block continually rubbing on the wheel tread or from short applications of heavy braking. The presence of scale may cause wheel/rail noise. Due to insignificant operating safety consequences, Class 3 scaled wheels do not warrant an in-service action, however its occurrence may indicate the onset of a brake system malfunction and thus should be investigated further. JHR UNCONTROLLED WHEN PRINTED Page 21 of 37
RESTRICTION: No speed restriction is required for any vehicle with class 3 scale, however, Trim Blocks may be used on multiple unit trains and cast iron brake blocks on locomotives, locomotive hauled vehicles and rail-bound infrastructure maintenance vehicles, to dress the wheel tread surface. 4.5.2 Class 4 scaled wheel Photograph 12 Example of a Class 3 Scaled Wheel Class 4 scale will have a measurable scale height not exceeding 15 mm. All Vehicles: Under no circumstances must a wheel with a Class 4 defect be allowed to enter service if found at a pre-trip examination or at a depot. Locomotives: If the defect is found en-route or at a location with no repair facility, the vehicle must clear the section subject to the speed restrictions shown below provided use of independent brake can be kept to an absolute minimum. Passenger vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle must clear the section subject to the speed restrictions shown below provided the relevant brakes can be isolated and/or the use of wheel tread brakes can be kept to an absolute minimum. JHR UNCONTROLLED WHEN PRINTED Page 22 of 37
CRN Engineering Standard CRN RS 011 Photograph 13 Example of a Class 4 Scaled Wheel Freight vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle must clear the section subject to the speed restrictions shown below provided the relevant brakes can be isolated and/or the use of wheel tread brakes can be kept to an absolute minimum. Rail-bound infrastructure maintenance vehicles: If the defect is found en-route or at a location with no repair facility, the vehicle must clear the section subject to the speed restrictions shown below provided the relevant brakes can be isolated and/or the use of wheel tread brakes can be kept to an absolute minimum. All vehicles: Once the section has been cleared, the vehicle shall not be further moved until: the scale build-up has been completely removed by grinding, chiselling, etc., or a wheelset/bogie change has been carried out, or a pony bogie is fitted. If a pony bogie is fitted, the vehicle shall then be transferred to the nearest depot in accordance with section 4.2.5.1. Upon arriving at a depot/workshop, an abrasive brake block may be used to clean the tread to restore it to unrestricted operation. Bogies which have had wheels with class 4 scale must have their running gear thoroughly examined for evidence of loose or adrift components particularly JHR Issued October, 2016 UNCONTROLLED WHEN PRINTED Page 23 of 37 Version 2.0
in the axlebox and traction motor areas. The vehicle brake system shall also be checked for correct operation and sensitivity. RESTRICTIONS: All vehicles with Class 3 wheel scale shall be restricted to the following speeds: Scale height 1 mm up to 5 mm Scale height greater than 5 mm up to 10 mm Scale height greater than 10 mm up to 15 mm 25 km/h maximum 15 km/h maximum 5 km/h maximum 4.5.3 Class 5 scaled wheels Class 5 scale will have a measurable scale height greater than 15 mm. 4.6 Arrises All Vehicles: Under no circumstances shall the vehicle be moved until the tread surface defect is adequately rectified. This can be achieved by in-situ grinding or chiselling. After rectifying the defect in the section, ensure that the vehicle is moved to the nearest siding at a speed which is applicable for class 4 scaled wheels. Once the vehicle is in the siding, it shall not be further moved until: the scale build-up has been completely removed by grinding, chiselling, etc., or a wheelset/bogie change has been carried out, or a pony bogie has been fitted. If a pony bogie is fitted, the vehicle shall then be transferred to the nearest depot in accordance with clause 4.2.5.1. Bogies which have had wheels with class 5 scale must have their running gear thoroughly examined for evidence of loose or adrift components particularly in the axlebox and traction motor areas. Bearings shall be rumble tested and visually inspected with the removal of the front cover or gas plug. The vehicle brake system shall also be checked for correct operation and sensitivity. Wheel treads shall be examined for any evidence of thermal cracking. An arris is the sharp edge or protrusion formed by the intersection of two surfaces. In the context of this standard, an arris occurs at the tip of a flange due to metal flow towards the tip from the flange face area, where the flange normally works against the rail gauge face during curve negotiation. The significance of an arris in a railway operation is its potential ability to split or climb over a set of facing points and thus derail a vehicle. The actual position of the arris relative the flange face and the steepness of the flange face is an important relationship. 4.6.1 Class 1 arris For the purposes of interpretation of this standard, Classes 1 and 2 arris classifications are not relevant. 4.6.2 Class 2 arris A class 2 arris is any protrusion above the flange tip up to 1.5 mm high. There is no action required for a wheel with a class 2 arris. JHR UNCONTROLLED WHEN PRINTED Page 24 of 37
Up to 1mm high above the tip of the flange and where the arris is rolled slightly back towards the flange tip Up to 1.5 mm high above the tip of the flange and where the arris is rolled back towards the flange tip. Figure 6 Diagram examples of a Class 2 arris 4.6.3 Class 3 arris A class 3 arris is any protrusion greater than 1.5 mm high or a distinct corner produced by a flat flange tip at the top of a steep flange face. A distinct corner produced by a flat on the flange tip in combination with a steep flange running face. See Section 4.7 on Steep Flanges From 1 mm up to 1.5 mm high above the tip of the flange and extending straight from the flange running face. See Section 4.7 on Steep Flanges Over 1.5 mm high above the tip of the flange and where the arris is rolled back towards the flange tip. Figure 7 Diagram examples of a Class 3 arris JHR UNCONTROLLED WHEN PRINTED Page 25 of 37
Wheel flange tips such as these should be removed either by wheel turning, by the use of an abrasive block with flange grooving, or by some suitable grinding operation. As a temporary measure the arris may be hammered down at the location to allow the vehicle to be moved as per a lower classification of defect. Locomotives: Locomotives must have inspection details recorded by the operator and be scheduled for wheel turning within 14 days of detection. Passenger vehicles: Vehicles must have inspection details recorded by the operator and be scheduled for wheel turning within 14 days of detection. Freight vehicles: Vehicles must be worked out of service for repairs Rail-bound infrastructure maintenance vehicles: Vehicles must have inspection details recorded by the operator and be scheduled for wheel turning within 14 days of detection. RESTRICTION: No specific operational restrictions except those specified above. 4.6.4 Class 4 arris A class 4 arris is the combination of a near vertical flange running face and an arris greater than 1.5 mm high. An arris greater than 1.5 mm high above the tip of the flange and extending from a steep running face. See Section 4.7 on Steep Flanges New wheel profile Figure 8 Diagram example of a Class 4 arris All vehicles: Under no circumstances must a wheel with this defect be allowed to enter service if found at a pre-trip examination or at a depot. If the defect is found en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a safe speed not exceeding 40 km/h over normal track and not exceeding 25 km/h over points, turnouts or crossings. As a temporary measure the arris may be hammered down at the location to allow the vehicle to be moved as per a lower classification of defect. The arris may be ground off for a permanent measure. RESTRICTIONS: All vehicles with a Class 4 arris shall be restricted to the maximum speeds specified above. JHR UNCONTROLLED WHEN PRINTED Page 26 of 37
If these restrictions unduly affect vehicle/train operations, the vehicle/train must be immediately removed from service to the nearest available siding. The relevant vehicle may then be repaired (bogie/wheelset change) at that location. 4.7 Steep flanges A visual examination of the wheel will be necessary to determine if it has a steep flange. A steep flange in conjunction with an arris or a distinct edge created by a flat topped flange has the potential to create a derailment situation at a misaligned track joint or a facing points blade. 4.7.1 Class 1 steep flange A class1 steep flange occurs when the flange face angle is 5 degrees or less to the vertical. Steep flanges that are not associated with an arris or flat top flange are classified as class 1. There are no arris classes 2, 3 or 5. A steep flange in conjunction with a class 3 arris is classified as a class 4 defect and shall be treated as per section 4.6.4. A flange is considered to be steep when the flange face touches the gauge anywhere above the notch. Figure 9 Application example of the steep flange gauge RESTRICTION: There is no speed restriction for any vehicle with steep flanges provided an arris or flat top flange is not present. JHR UNCONTROLLED WHEN PRINTED Page 27 of 37
A flange is considered to be steep when the flange face angle in this area is 5 degrees or less to the vertical. 16 mm above the tread line 70 mm Figure 10 Example diagram 1 of a class 4 steep flange Figure 11 Example diagram 2 of a class 4 steep flange 4.8 High flanges A visual examination of the wheel with the hook gauge will be necessary to determine if it has a high flange. Note: High flange classes 1, 2, 4 and 5 are not relevant. 4.8.1 Class 3 high flange A flange is classified as a class 3 high flange when the tip is 35 mm above the tread centre line. All vehicles: Vehicles found with a high flange at a depot or pre trip examination shall not be permitted to enter service. Locomotives: Locomotives with high flanges must have inspection details recorded by the operator and be scheduled for wheel turning within 14 days of detection. Passenger vehicles: Vehicles with high flanges must have inspection details recorded by the operator and be scheduled for wheel turning within 14 days of detection. Freight vehicles: Vehicles must be worked out of service for repairs. Rail-bound infrastructure maintenance vehicles: Vehicles with high flanges must have inspection details recorded by the operator and be scheduled for wheel turning within 14 days of detection. JHR UNCONTROLLED WHEN PRINTED Page 28 of 37
RESTRICTIONS: There is no speed restriction requirement for any vehicle with high flanges. When the hook gauge touches the flange tip the flange is too high 35 mm above the tread line 70 mm Figure 12 - Application example of the flange height gauge Refer to Figure 18 for flange height and thin flange gauge 4.9 Hollow tread A visual examination of the wheel with the hollow tread gauge will be necessary to determine if a hollow tread is evident. Note: Hollow tread classes 1, 2, 4 and 5 are not relevant. 4.9.1 Class 3 hollow tread The maximum permissible tread hollowing is 3 mm nominal, as determined using the wheel gauge as shown in Figure 11. Refer to Figure 20 for wheel hollow tread gauge. For wheels found with hollow tread, the following applies: Locomotives and passenger vehicles must have inspection details recorded by the operator and be scheduled for wheel turning within 14 days of detection. Freight vehicles must be worked out of service for repairs. No speed restriction for any vehicle with a hollow tread. JHR UNCONTROLLED WHEN PRINTED Page 29 of 37
Any gap at this point indicates excessive tread hollowing 70 mm 120 mm 4.10 Thin flanges Figure 13 - Application of a hollow tread gauge A visual examination of the wheel will be necessary to determine if a thin flange is evident. Note: Class 1 thin flange, class 2 thin flange, and class 3 thin flange classifications are not relevant. 4.10.1 Class 4 thin flange The minimum allowable flange thickness is 19 mm. The maximum allowable tread hollowing shall be 0.5 mm, measured below the highest point on the outer tread surface, beyond the 120 mm dimension shown. Under no circumstances must a wheel with a flange thickness of 19 mm or less be allowed to enter service if found at a pre-trip examination or at a depot. 19 mm 10 mm Full Flange Profile Figure 14 - Thin flange JHR UNCONTROLLED WHEN PRINTED Page 30 of 37
If a vehicle is found with a wheel flange thickness of less than 19 mm, down to a minimum of 18 mm, en-route or at a location with no repair facility, the vehicle may continue through to the scheduled destination and/or be transferred to the nearest depot at a speed of not more than 40 km/h. The recommended method for detecting a thin flange is using a "hook gauge". (see Figure 13) A thin flange will be detected when the end of the gauge touches the tread surface of the wheel. Note: In this case any arris present on the flange must be removed completely. 4.10.2 Class 5 thin flange If a vehicle is found with a wheel flange thickness of less than 18 mm the vehicle must be immediately removed from service. If this portion of the gauge touches the wheel tread, the flange is too thin Figure 15 - Application of thin flange gauge Refer to Figure 22 for flange height and thin flange gauge 4.11 Short flange A visual examination of the wheel will be necessary to determine if a short flange is evident. Note: Class 1 short flange, class 2 short flange, class 4 short flange, and class 5 short flange classifications are not relevant 4.11.1 Class 3 short flange In some cases where rapid flange wear takes place, without significant tread wear, a worn wheel profile is produced having a ramp at the root of the flange. This ramp effectively shortens the flange thereby allowing the gauge corner of the rail to work closer to the flange tip. This arrangement reduces the safety margin for wheel climb derailments. The short flange gauge is designed to arrest this phenomenon before it becomes critical. JHR UNCONTROLLED WHEN PRINTED Page 31 of 37
The flange is too short if clearance exists here between the gauge and the tip of the flange, after removal of any arris. For a correct indication, the short flange gauge must be in contact with the wheel tread and flange at these two points. Figure 16 - Application of short flange gauge Refer to Figure 23 for short flange gauge. 4.12 Misaligned brake gear Inspection for overhanging brake blocks or misaligned brake gear must be carried out with the brakes applied. 4.12.1 Temporary brake block overhang In the case where an overhanging brake block is found and there is no evidence of shouldering on the brake block or wheel tread and no evidence of class 4 thermal cracks, then the overhanging brake block may be a temporary condition. Consideration must be given to the lateral float of the wheelset together with brake rigging clearances to determine if the brake block is overhanging temporarily. If evidence suggests that the brake block overhang is temporary then the vehicle is suitable for service subject to regular inspections of the brake block(s) in question. Locomotive and passenger vehicles with brake gear in this condition are to have the defect recorded and be inspected at the next routine inspection. On vehicles where brake rigging is tied together laterally there should be no excuse for overhanging brake blocks, and if found corrective action must be taken to adjust the rigging or replace worn components such as brake heads, pins and/or bushes. If there is evidence of any other wheel tread surface defect the vehicle shall be attended to as per the relevant section of this standard. Where non-metallic and/or segmented brake blocks are used, particular attention shall be paid to the presence of thermals and skids. JHR UNCONTROLLED WHEN PRINTED Page 32 of 37
If a shoulder has worn on the edge of the brake block face, then action shall be as per clause 4.12.2. Important: Non-metallic blocks will not exhibit a pronounced shoulder as the overhanging area tends to break away before achieving any noticeable size unless the overhang is excessive. Figure 17 Diagrammatic example of a temporary overhanging brake block 4.12.2 Permanent brake block overhang. In the case where an overhanging brake block is found and determined to be a permanent fault by evidence of a shoulder on the wheel tread, a shoulder on the brake block face and/or class 4 thermal cracking at the edge of the wheel tread, then that vehicle shall not be permitted to enter service until the matter is rectified Figure 18 - Example of permanent brake block overhang Pronounced step in the tread caused by a permanently overhanging brake block, forming a false flange Figure 19 - False flange due to brake block overhang JHR UNCONTROLLED WHEN PRINTED Page 33 of 37
5 Weld repairs of wheel skids The repair of wheel skids by welding is a temporary measure permitted to allow recovery of a vehicle with class 5 wheel skids, as outlined in section 4.4.5. After weld repair the vehicle must proceed directly to the nearest repair facility for wheelset change or re-profiling. A suitable weld procedure must be developed for the repair. Notwithstanding this, welding shall be carried out circumferentially, not transversely across the tread. All surface irregularities and deposited weld metal shall be ground smooth to the contour of the wheel after the welded area has cooled to ambient temperature. The surface of the weld, and adjacent area shall be inspected for flaws prior to movement of the vehicle. Once the vehicle has been moved to a suitable repair location for wheel turning, all weld metal, including the heat effected zone, must be removed, and the wheel surface inspected for possible flaws, prior to replacing the vehicle into service. 6 Wheel tread profile re-machining 6.1 Surface finish It is important when re-machining the wheel tread and flange profile that the surface finish be maintained within acceptable limits. This is to ensure that surfaces which can normally contact the rail and/or check rail are smooth, free of machine chatter marks, surface waviness or grooving, which could contribute to a wheel flange climb type derailment. The surface finish of the wheel tread and flange, after machining shall not exceed 12.5 μm (micrometres) RA (Roughness Average). Undercutting, grooving or waviness of the tread surface between the flange root radius and the outer edge of the tread, is permitted but shall not exceed 0.25 mm in depth below the true tread profile. Localised undercutting, grooving or waviness of the flange profile between the wheel tread side of the flange root radius and the back face of the wheel, is permitted but shall not exceed 0.25 mm in depth below the true flange profile. 6.2 Witness marks Witness marks used for an indication of machining efficiency, are permitted on the flange face, between a point 10mm above the wheel tread baseline and the tip of the flange but shall not exceed 6 mm in width. 6 mm Figure 20 An acceptable machining witness mark JHR UNCONTROLLED WHEN PRINTED Page 34 of 37
Figure 21 An unacceptable machining witness mark Figure 21 depicts examples of unacceptable wheel turning witness marks. The top photograph demonstrates an unacceptably deep groove which has resulted in a false flange. The bottom photographs show a shallow but wider groove on the flange face which could contribute to a wheel climb derailment. 6.3 Machining Tolerance The tolerance of a re-machined wheel tread and flange profile shall not deviate below the true profile by more than 0.25 mm. That is, it shall not be possible to insert a 0.25 mm feeler gauge beneath a profile gauge positioned on the wheel tread. 7 Examination of tyred wheels in service Tyred wheels must be inspected prior to each trip for relative movement between the tyre and wheel centre. If any relative movement is detected between the tyre and wheel centre, the vehicle must be immediately removed from service. JHR UNCONTROLLED WHEN PRINTED Page 35 of 37
8 Overheated wheels Any wheel which has become severely overheated due to excessive braking or dragging brakes, is a class 4 defect. An overheated wheel can be identified by a blueing discolouration, and may be evident after a skidded wheel or dragging brake incident. Under no circumstances shall a wheel with a class 4 defect be allowed to enter service if found at a pre-trip examination or at a depot. If the defect is found en-route, or at a location with no repair facility, the vehicle may continue through to the scheduled destination, and /or be transferred to the nearest depot at a speed of not more than 40 km/h, providing the brakes are isolated (passenger and freight) or the use of independent brake can be kept to an absolute minimum (locomotives). If these restrictions unduly affect operations, the vehicle must be immediately removed from service. The vehicle shall then be repaired (bogie/wheelset change) at the location where the defect was found. Wheels which have been severely overheated must be thoroughly inspected for possible thermal defects and checked for changes in metallurgical structure. If there is any doubt as to the structural integrity of the wheel, and the heat affected area cannot be removed by machining, then the wheel must be scrapped. Severely overheated wheels also affect bearing lubrication therefore it is essential that bearing be checked for heat effects and adequate lubrication. Overheated tyred wheels must be removed from service and replaced immediately. 9 Wheel gauges R 9.5 35 R 4 mm R 2 mm 70 13 mm 4.5 mm 24 mm Tolerance on dimensions +/- 0.2 mm Due to the introduction of the WPR 2000 wheel profile, these dimensions have been reduced by 1.5 mm to effectively maintain a 19 mm minimum flange thickness. JHR UNCONTROLLED WHEN PRINTED Page 36 of 37