Technical specification of wheel Dynamometer

Transcription

1 1.1 General Technical specification of wheel Dynamometer Established in 1984, Rail Wheel Factory (RWF) located at Yelahanka in Bangalore is a major production unit of Indian Railways. ISO 9001:200 certified RWF manufactures high quality wheels and axles for all types of Rolling Stocks with Indian Railways i.e. coaching, freight and traction (locomotives). RWF has adopted cast wheel technology developed by M/s Griffin Wheel Co USA. RWF has been manufacturing wheels of deep disk parabolic design and has capability to manufacture wheels ranging from 725mm to 1100 mm diameter. For users of forged wheels, RWF offers support for design and manufacture of equivalent cast steel wheel meeting the user s requirements. RWF work on development of cast steel micro-alloyed wheels for locomotive applications has shown promise. The present production of RWF is about 200,000 wheel discs of various sizes every year. In addition to rail wheels, RWF also manufactures axles and complete wheel sets. Wheel sizes and standards generally produced by RWF are as given below: Application Wheel Dia Standard Freight mm AAR-M-208 and IRS R-19 Cl. B Passenger mm IRS R-19 CI. A Traction/Locomotives 1092 mm IRS MP RWF is setting up a modern Wheel Design, Development and Testing Centre (DDTC) at its works in Yelahanka, Bangalore. The centre will have facilities for developmental testing of wheels in accordance with major international standards, including a modern wheel Dynamometer for testing of rail wheels. The dynamometer shall be used for developmental testing of wheels and shall be capable of simulating various static, dynamic loads (both mechanical and thermal) and also operating parameters to which wheel is subjected in real life. Primary function of the dynamometer shall be to test the wheel disks. Wheels have to be subjected to mechanical rolling loads, thrust load, and thermal loads resulting from brake application. Testing of brake blocks and brake pads can be taken as secondary objective. This document covers the technical requirements, design, inspection, installation, commissioning, spares, after sales service and training of personnel in proper handling and maintenance of the dynamometer and its accessories. Details of existing Brake Dynamometer of Indian railways installed at Lucknow are given at Annexure-A, for reference. However, this equipment is meant only for testing brake blocks and not for testing wheels. This is for reference only. The equipment offered shall work satisfactorily under prevailing ambient conditions at Bangalore. The tenderer shall specifically and clearly provide air-conditioning and sound insulation requirements and shall submit details of electrical and civil engineering layouts along Page 1

2 with the tender. The ambient temperature varies between 5 C to 50 C (Within the equipment hall the maximum temperature may be 45 C) and the relative humidity may be as high as 85-90% during monsoon. In case some component would need extra protection, the supplier shall take care of such additional protection. The complete dynamometer shall be designed on a modular concept so as to facilitate addition of any additional/optional equipment by the purchaser as and when considered necessary Test Objectives The objective of the tests to be conducted on the dynamometer is To validate wheel design calculations like FEA results, fatigue analysis and thermal analysis. To test for shelling, spalling, thermal cracking and other failures of wheels To test and ascertain thermal input at which stress reversal occurs up on drag braking test Dynamometer shall be capable of simulating operating conditions and apply loads in accordance with international standards for rail wheel design. Tests are required to be carried out on freight car wheels, passenger car wheels and locomotive wheels. The Dynamometer shall have following test function capabilities. 1. It should simulate rolling contact (between rail and wheel) and apply the vertical load on the test wheel. This can be done through a rotating wheel (simulating rail track) against the test wheel. Rolling contact parameters should be similar to actual operating conditions on IR. 2. It should simulate lateral thrust load on the test wheel for simulating curve negotiation. This can be done by applying oscillating lateral thrust loads. 3. The Dynamometer shall be used for evaluating resistance of rail road wheels to simulate: a. Shelling, spalling, wear and thermal cracking of tread surface. Sudden failure in the rim resulting from stress built-up caused by brake shoe action. b. Fatigue failures c. Other failures including those caused by mechanical and thermal loadings. Therefore, it should be capable of simulating the required test as per predefined programme for a long period. It should be able to simulate thermal loads caused by brake application. Thermal load application shall be carried out for both brake stopping tests and drag test as per relevant international standard. Since thermal loading will be applied through application of brake blocks, therefore, Dynamometer is expected to have capability to test brake blocks as per UIC/AAR specifications for both brake stop tests and drag tests. Arrangement for testing brake pads should also be provided. It should also be possible to carry out wet testing as per UIC/AAR specification. Page 2

3 Series of tests that are proposed to be carried out using this dynamometer is provided on Annexure- B Loading Requirements The dynamometer shall be capable of simulating both mechanical and thermal loading conditions (through closed loop servo control) on test wheel that duplicates or exceeds the service condition requirement of similar wheels in IR and it should also be capable of simulating forces in accordance with relevant international standards such as AAR S -660/UIC 510-5/EN 13979/EN etc. A list of relevant specifications is provided for reference at Annexure D. Tenderer may offer his suggestions regarding any other specification to be considered. Service conditions such as axle load, maximum brake force, lateral loads, and speed and wheel diameter of wheels are given below Rolling Stock Parameters Axle load of different type of rolling stock along with wheel diameter and maximum operating speed is given below. These represent maximum values based on which capacity of dynamometer has to be designed. Rolling stock at lower axle load and speeds continue to operate over IR and Dynamometer should be capable of testing their wheels also. Wheel dia Axle load Speed Type of Rolling Stock 915 mm 20.0 t 300 kmph Passenger car 1000 mm 25.0 t 150 kmph Freight car 1100 mm 20.0 t 300 kmph Locomotive 1000 mm 32.5t 150 kmph Freight car 1098 mm 24.0t 140 kmph Locomotive Wheel diameters of the IR Rolling Stock are indicated in the table above. However, the equipment shall have capability of testing wheels of sizes varying from 38 to 48 (762 mm to 1219 mm) in diameter. Geometric details of wheels manufactured by RWF are available at Annexure- C. (For reference only) Brake Force Brake force on present rolling stock under operation over IR is as given below: Type of rolling stock Freight car Passenger car Locomotive LHB coach Brake force 4.8 tonnes for L type brake block and 2.3 tonnes for K type brake blocks. (Acting through single brake block on wheel tread) Clasp Type brake system 3 t for K type brake block 8.0 tonnes CI/Composite brake block-clasp type brake system Disc brake application up to 12t/disc Page 3

4 Dynamometer capability shall be as given below: 1. Brake shoe force shall be 6,000 kg acting through single brake block on wheel tread 2. Brake block force per wheel 0.25t to 12 t in case of clasp braking with L type/ci type brake blocks 3. Brake block force per wheel 0.25t to 7 t in case of clasp braking with K type brake blocks 4. In case of disc brakes it should be possible to test disc brake pads upto 12t/disc. 5. It shall be possible to adjust the brake force steplessly from minimum to maximum from the dynamometer consol Vertical Loads It should be possible to apply upto maximum vertical load of the value equal to twice the static wheel load as per AAR S-660- requirements (defined as V1 and V2) Lateral Loads It should be possible to apply Lateral load of the value equal to the vertical static load as per AAR S-660- requirements (defined as L1). Lateral oscillating load should also be applied to simulate curve negotiation at a suitable frequency range. Minimum specified oscillating is frequency of 1Hz and minimum yaw angle is 1 degree. (Tenderer to indicate if better capability can be provided - IR permits curves of upto 10 degree. (175 m radius)) Thermal Loads 1. The Dynamometer shall be capable for applying thermal loads by single shoe brake blocks as well as clasp brake arrangement on wheel tread. It should also have capability of applying loads through disk brakes (both axle mounted as well wheel mounted disk brakes). It should be possible to apply thermal loads in accordance with UIC/AAR/IR loading conditions as applicable to IR for both stopping as well as drag braking. 2. Dynamometer shall be capable of thermal loading as per AAR S-660 which specifies thermal loading of specified HP for 20 minutes depending on axle load and application. 3. Dynamometer should also have capability of thermal loading as per UIC specification which are more severe and specify braking power of 50kW for 45 minutes for 22.5t axle load at a speed of 60 km/h, and 840 to 1000mm diameter application. 4. The Wheel Dynamometer is required to have minimum torque range of Nm. The Dynamometer Designer shall supply calculations to determine the torque range as per the test requirement including drag braking Technical Requirements The test wheel will be subjected to vertical load and rolling contact through replaceable friction driven rail in the form of continuous ring of suitably heat treated rail mounted on a fabricated wheel (follower rail wheel). The dynamometer shall be equipped with suitable grinding wheels to Page 4

5 maintain the rail profile so that desired rail wheel contact can be maintained. Appropriate arrangement for cooling the follower rail wheel shall be made so that it can safely operate in all operating and test conditions. Follower rail wheel shall have UIC 60 rail profile. In order to cover the operating requirements of Indian Railways, proposed speed requirement of the dynamometer is rpm and Inertia requirement is kgm². The tenderer shall supply all the calculations and verify the Inertia requirements. The dynamometer shall not exceed 300 seconds to achieve the maximum speed with corresponding inertia. However, the deceleration of the wheel shall be subject to applied brake force. The tenderer shall submit detailed performance and physical specification of the dynamometer that shall include rating per wheel covering minimum and maximum mass range, rated speeds corresponding to minimum, intermediate and maximum mass along with calculations and formulas used. For running the dynamometer, a suitable drive motor capable of running the machine at speeds and axle loads will be preferred and the capacity of the motor shall be decided by the supplier. The tenderer shall also submit calculations in support of selection motor rating. The motor shall have facility to run at any speed between minimum and maximum designed speed with stepless speed control. The electric supply at RWF is 3-phase 440 V AC at 50 Hz. The tenderer shall provide required system for converting AC supply to DC. Tenderer shall select DC/AC drive based on his proven experience and capability and submit suitable justification for the drive selected. Simulation of Kinetic Energy of the Vehicle: A suitable hybrid system consisting of mechanical fly wheels and electrical inertia simulation shall be used for simulating the kinetic energy of the running vehicle. Simple hydraulic/mechanical shifting device shall be used for engaging/disengaging the flywheels with the drive shaft. It would be desirable to have optimum simulation of inertia electrically to reduce overall size of the machine and the motor. Tenderer to confirm that appropriate arrangement to feed the power back to mains safely without disturbing the power supply during electrical inertia simulation are made. Based on the requirements of axle-load, wheel diameter and speeds given above, the tenderer shall submit the calculations for selection of fly-wheels and electrical inertia simulation for each combination and decide the power requirement and speed of the D.C. motor. The tenderer shall clearly indicate the number of flywheels and electrical inertia simulation to cover conditions given in para and support it by detailed calculations. A provision shall be available to run the dynamometer at constant speed (simulating drag braking conditions) with variation in set speed within 2%. During drag braking, it should be possible to apply a constant braking torque. Test Brake Suspension Arrangement The arrangement for connecting wheel/discs with the dynamometer shall be kept as simple as possible. Arrangement of clamping of wheel /discs with dynamometer would be preferred instead of force fitting them on to the stub axle and then coupling with dynamometer shaft. The Page 5

6 arrangement shall ensure that the wheels/discs under testing are concentric with dynamometer main shaft. Suitable arrangement for mounting/dismounting of test wheel on the stub axle shall be provided by the supplier as an accessory. Supplier shall also provide drawings of the proposed arrangement. For fixing of brake blocks/pads, an arrangement shall be provided by the tenderer where the location of brake blocks and brake pads is adjustable in all the three plains, depending on the requirements. The suspension rods holding brake blocks should be in vertical position during brake application and the variation from vertical position shall not be more than 2% of the length of the suspension rods. In no case the brake blocks should touch the wheel except at the time of brake application. The clearance between the wheel and brake block should be uniform. In case of disc brakes, pad holder shall be fitted such that they can rotate about vertical axis so that the pads can be adjusted freely. Suspension rods for the pad holders shall be in vertical position when brakes are applied. Here again the variation from the vertical shall not exceed 2% of the length of the suspension rods. The system shall be able to account for the following brake parameters by suitable adjustments within the range of accuracies mentioned below: a. Inertia 1% for V 40 kmph) 2% for V < 40 kmph) b. Rotational speed 0.2% c. Contact force 1.25% d. Tangential force 1% e. Braking torque 1% Brake actuation of tread/disc brake shall normally be with the help of compressed air Cooling A variable speed blower of suitable capacity shall be provided for cooling and simulating wind resistance. This shall be as per drag braking requirement which is to be carried out at a speed of 60 km/h as per UIC requirement. The blower shall be provided with filters at the inlet to ensure that cooling air is dust free to the extent required by the machine. A variable speed exhauster shall be provided for taking out dust and fumes emitted from the test space with arrangement for controlling its speed. The volume of air to be driven out by exhauster shall be more than that of the blower for the same speed. Speeds of blower and exhauster should be controllable from the control room Data Acquisition System A data acquisition system with latest hardware and Windows based software shall be provided for acquisition, analysis, controlling and recording various parameters during braking. There should be a provision of about eight free channels for additional data acquisition if considered necessary at a later date. The suppliers shall use standard software and hardware with provision of obtaining following functions: Page 6

7 1. Variable filling time between 0.5 to 6 sec. 2. Setting of control parameters depending on mode of operation and installed brake system. 3. Control sequence during test run 4. Mass simulation 5. Collection of measured values of parameters 6. Checking of actual values of parameters with respect to set warning values and disconnection limits. 7. Arithmetical calculation - On line calculation of test data. 8. Transmission of measured data to PC 9. Presentation of data acquired and evaluated for printing in tabulation, graphical, bar chart form The data will be required to be stored on hard disk of the computer system. The complete data acquisition system should be integrated with the dynamometer drive unit and hard-ware and software of the computer system. Sample Digital Display list required on control console is given below. This shall be finalized at design stage. 1. Brake cylinder pressure. 2. Force on each brake block / brake pad 3. Braking speed in rpm 4. Rail speed in km/h 5. Brake time in seconds. 6. Brake energy 7. No. of brake applications 8. Run out revolutions after brake initiation 9. Braking distance in meters 10. Instantaneous and mean coefficient of friction ( ) 11. Brake torque 12. Temperature of brake block/ pads at six locations through non-contact temperature measuring signals from 0 to 1300 C 13. Temperature of wheel at sufficient locations through non-contact temperature measuring signals from 0 to 1300 C. (Tenderer to specify in his offer) 14. In case during braking if the wheel locks even for a very small time, it should be displayed on the control desk and shall be recorded on the Data Acquisition System. 15. Wheel shall be strain gauged at sufficient locations and stress value reported. (Tenderer to specify locations) 16. Vertical force 17. Lateral force 18. Yaw angle 19. Frequency of oscillating lateral force 20. Wheel rim displacement (Ref: EN 13979) Page 7

8 The following output is required from data acquisition system for presentation in the report in graphical, bar chart and tabular form. 1. Wheel and brake block temperatures at different locations Vs time during braking operation and also for set of readings. 2. Wheel stress values at different locations w.r.t load applied 3. Result in tabular form indicating sample number, reading number, speed (Kmph/rpm), braking time. ROR, Energy a (from instant of brake application and also after 95% of brake power), initial and final temperature of brake block and wheel. 4. Number of cycles with reference to performance tests at Annexure C CONTROL It shall be possible to control all commands and nominal values, relevant for dynamometer to be set in the automatic system. Real values should be collected and logged. It should also be possible to set up pages for display of data on real time basis as well as after the completion of each braking operation depending upon the requirement. The dynamometer control system shall be software based operating under a Microsoft Windows based system to monitor and control all machine functions, as well as to acquire test information and generate the appropriate reports. The system shall interface with the drive, the controlled brake actuation system and other sub-systems to achieve the desired test conditions. Instrumentation to be provided for feedback from all measurement devices for control and data acquisition. This provides advantages over a traditional multi-bay console. By immediately converting all analog data signals to digital format, there is a significant decrease in signal noise. The control computer provides real time data display, last stop summary data, test stand control, and data acquisition. Tenderer to provide details of signal conditioning and its various modules. Proven control software shall be used which shall be customized in consultation with RITES. Software for analysis of results and preparation of reports shall also be provided. Necessary software for the above shall be developed by the supplier in consultation with RITES. The limiting values for Dynamometer safety with respect to axle load, RPM, brake force or a combination of these shall be set by the supplier in the controlling computer Safety Devices for Wheel Dynamometer In order to prevent injuries to the operating staff and damage to the dynamometer machine due to human error, necessary safety devices should be provided. All failures should be displayed on the PC and should preferably result in an audio warning also. A few of them are enumerated below. 1. A protective cover above the rotating parts and electric motor etc. should be provided. Suitable enclosure for portion where braking is taking place, should have a transparent portion also, as per international safety practices. The protective cover should be prevented from getting opened when the dynamometer is running. However, in a special Page 8

9 circumstance when the operator wishes to actually see the operation going on inside, it should be possible to manually override this interlocking feature. 2. The brake dynamometer should not run beyond the pre set rpm 3. Indicating lights shall be provided on the control table to glow in case temperatures of any bearing exceeds the maximum limit. If appropriate action is not taken on this warning, the dynamometer should shut off automatically. 4. In order to monitor high or low voltage supply, a separate cut off switch should be provided, which will automatically control the drive motor. 5. In case of failure of the cooling system of the drive motor, the drive motor should automatically come to stand still and indication of the overheating of the Drive motor should be displayed on the control console. 6. Safety should be provided against over/under current of the motor windings. 7. Malfunctioning or failure of the blower/exhauster system (test bed cooling and ventilation), lubrication etc. shall be indicated on the control console and the system shall automatically stop or revert to safe configuration. In general safety functions must respond to the following defects/operating conditions in addition to other conditions which the supplier may feel necessary: 1. Actuation of any emergency stop button 2. Opening of the protective covers while the dynamometer is running. 3. Excessively high temperature of any main bearing. 4. Various malfunctions of AD/DC converter unit. 5. Various malfunctioning of auxiliary drives 6. Excessive speed, armature voltage, current, temperature etc OTHER REQUIREMENTS Thermal imaging camera as per particulars given below: Thermal Imaging Camera System: - Description Infrared non-contact temperature imaging - Video Update 7.5 Hz, 320 x Operating Temperatures (-40 to 120), (0 to 500), (200 to 2000) C Video monitoring system: Video Monitoring System - Description System provides the ability for dynamometer operators to visually monitor tests at the dynamometer with one camera. Also provides time based recording integrated with test data to allow playback of video with stop data. - Lens Color and adjustable zoom function - Working environment As per requirement Page 9

10 Displacement measuring system: Non-Contact Capacitance Probe Displacement Measurement Description This option measurement system uses non-contact capacitive sensors capable of making very small displacement measurements. Includes Dyno Fixtures, Signal Conditioning Rack, and Capacitance Probes Channels 8 Fixture Mechanical apparatus to position as many as three probes on either side of the rotor Signal Signal conditioning rack to provide a voltage signal proportional to conditioning displacement Self calibration kit to be included Emergency Braking: Emergency brakes should be provided to act as safety brakes for stopping the dynamometer in the shortest possible time in case of an emergency. It should be so designed that the actuation of the emergency brakes is guaranteed even in case of power failure. Spring applied & pneumatically release type arrangement would be preferred for emergency brakes. Several actuation switches for emergency braking of dynamometer shall be provided at easily accessible locations in control room, equipment room and on the Dynamometer machine itself. The tenderer shall also indicate the braking torque of each jaw and also the diameter of the disc and stopping time for emergency braking Installation and Commissioning Complete installation of dynamometer along with all the accessories will be carried out by the manufacturer/supplier at the DDTC at RWF Bangalore. This would include clearance from custom in India and inland transportation in India. It shall also include crane facilities, if required, during installation. Commissioning by the supplier will follow installation at DDTC. The supplier shall demonstrate one full series of testing sequences as a part of commissioning test USER TRAINING The supplier/manufacturer shall make provision for imparting training to RWF persons at RWF regarding the operation and use of equipment, its accessories and software for the intended applications and troubleshooting after receipt of the machine at RWF. The details of training plan shall be indicated in the offer. Training at Supplier/Manufacture s works shall also be provided free of cost as desired by user. The cost of lodging and travelling will be borne by Buyer. Page 10

11 EXISTING BRAKE DYNAMOMETER AT RDSO, LUCKNOW, INDIA Annexure-A The existing Brake Dynamometers is housed in a hall measuring 28 x 10 meters. The actual Dynamometer measures 10x28x2.1 m. Broad technical details of the Dynamometer are as under: TECHNICAL DATA: 1. Max.(total) gyrating mass : 320 kgfms² 2. Minimum (basic) gyrating mass (with motor) : 66 kgfms² 3. Increments of gyrating masses (selectable) : 2 kgfms² 4. Sizes of the 7 gyrating masses which can be engaged and disengaged ( as desired) : 2,4,8,16,32,64 and 128 kgfms² 5. Maximum KE at 1300 rpm : 29.7x105 kgm 6. Minimum KE at 1300 rpm : 6.1x105 kgm 7. Maximum KE at 17 rpm : 525 kgm 8. Minimum KE at 17 rpm : 105 kgm 9. Drive rating (abs.) : 230 kw 10. Speed infinitely variable over full speed range up to Maximum of. 11. Rated torque of drive motor (abs.) (Constant in the low speed range to 635 rpm then decreasing hyperbolically to about 170 kg fm at 1325 rpm) : 1300 rpm : 350 kgfm 12. Maximum permissible brake torque : 4800 kgfm 13. Brake torque measuring range : kgfm 14. Pressure measuring ranges, pneumatic : 0-10 kgf/cm² 15. Pressure measuring ranges, hydraulic : kgf/cm² 16. Temperature measuring ranges selectable : C C 17. Maximum test specimen diameter : 1300 mm 18. Max. simulated road speed with 1000 mm diameter : 245 km/h wheel 19. Distance between the two mounting flanges with : mm infinitely variable adjustment. 20. Cylinder Pressure : Max kgf 21. Total connected value of plant (abs.) : 340 kw 22. Total current strength (abs.) : 600 A 23. Operating Voltage : 415V, 50 Page 11

12 Annexure-B SERIES OF TESTS TO BE CARRIED OUT ON THE DYNAMOMETER The objective of the tests to be conducted on the dynamometer is 1. To validate wheel design calculations like FEA results, fatigue analysis etc. from simulation as recommended by AAR/UIC/EN. 2. To test for shelling, spalling, thermal cracking and other failures 3. To test brake blocks and brake pads The test proposed to be conducted as specified in the above standards. Series of the tests to be done is summarized below for ready reference: A. Test to meet AAR- S-660 requirements: The following tests shall be carried with load combinations shown against them: 1. Test 1: Vertical + Lateral 2. Test 2: Vertical Only 3. Test 3: Thermal Load 4. Test 4: Vertical + Thermal 5. Test 5: Vertical + Lateral +Thermal The vertical, lateral and thermal loads shall be as defined in Clause 5 of AAR S-660 (Revised 2009). B. Test to meet UIC/EN requirements. 1. Test for verification of mechanical response: The applied forces and the test procedure are described in clause of UIC 510-5, May 2007 and Annexure B of EN :2003 respectively. 2. Test for verification of thermo-mechanical response: Parameters for Thermo-mechanical assessment of the wheel are defined in Clause 3.2 of UIC 510-5, May Procedures for dynamometer test are defined in Chapter 6 of EN :2003 C. Performance Tests. D. Brake Tests. 1. Wear, Spalling and Shelling tests 2. Effect of thermal loading on residual stress 3. Rolling contact fatigue. 1. Brake block and brake pad tests to UIC 541. Page 12

13 Annexure-C

14 Annexure-D LIST OF STANDARDS USED FOR WHEEL DESIGN/TESTING (PROVIDED FOR REFERENCE) 1. AAR S-660 : Manual of Standards and Recommended Practices for Wheels and Axles 2. ERRI Report B 126/RP 18 : Requirements for Brake Test Rigs 3. UIC Code 510-5: Technical approval of monobloc wheels 4. UIC Code 541-4: General Conditions for Testing Composite Brake Blocks 5. EN 13103:2007: Railway applications - Wheelsets and bogies - Non-powered axles; Design method, February EN 13104:2007: Railway applications - Wheelsets and bogies - Powered axles - Design method, February EN 13262:2006: Railway applications - Wheelsets and bogies - Wheels - Product requirements,january EN 13715:2005: Railway applications - Wheelsets and bogies - Wheels - Tread profile, May EN :2004: Railway applications - Wheelsets and bogies - Monobloc wheels Technical approval procedure - Part 1: Forged and rolled wheels, July EN :2009: Railway applications - Wheelsets and bogies - Monobloc wheels Technical approval procedure Part2: Cast Wheels, November IRS-R-19/93 (Prt I) - Indian Railways Standard Specification for wheels and axle assembly for carriage and Wagon 12. IRS-R-19/93 (Prt II- rev 3) - Indian Railways Standard Specification for Solid Forged Steel Wheels for carriage, wagon and EMU Stocks. 13. IRS-R-19/93 (Prt III) - Indian Railways Standard Specification for cast wheels for carriage and Wagon Page 14