SANS 1589: Braking Performance of Trackless Mobile Mining Machines Proposed Changes

Transcription

1 SANS 1589: Braking Performance of Trackless Mobile Mining Machines Proposed Changes Presented by : Paul Schutte Date: 15 November 2007

2 Workgroup Prof At von Wielligh UP (chairman) DME SABS Sasol Mining Anglo American Anglo Plat Barloworld Equipment Bhp Billiton Fermel Gearratio Komatsu Multibrake NCS Engineering Sandvik Bell

3 Reasons for Review of SANS 1589 To integrate and review the requirements of the following: SANS 1589 ISO 3450, Earth-moving machinery braking system of rubber tyred machines Performance requirements and test procedures. DME COP, DME 16/3/2/2 A2 Guidelines for the compilation of a mandatory code of practice on trackless mobile machinery. SANS and 2, Braking (motor and towed vehicles, designed for low speed or for use off public roads) Part 1: Low speed vehicles. Part 2: Low speed trailers. To include requirements for hydrostatic driven TMMM braking systems

4 Contents of Presentation Section added on safety. Changes in requirements.

5 SANS 1589: Scope This standard specifies requirements for the braking performance of trackless mobile mining machines (TMMM) that are used on mines The following categories of TMMM applies: underground mining machinery surface mining machinery vehicles and machinery used for both surface and underground operations

6 Trackless Mobile Mining Machines (TMMM)

7 Safety paragraph added For onsite testing purposes, the mine is responsible at all times for ensuring that safe working practices are employed and that the requirements of the Mine Health and Safety Act and Regulations of Act No. 29 of 1996 are adhered to. Not withstanding the above, or the guidelines in this standard, the mine remains responsible for examining the particular end use conditions and performing a risk assessment to evaluate particular operational hazards that may affect the safe stopping distances and brake efficiency requirements of the equipment under his control.

8 Annexures added Annexure A - Safety (informative) The mine shall assess the conditions where the TMMM will be used at the mine and shall prescribe the correct brake performance required for the TMMM at beginning of life and during its service life. The following section provides technical background for such risk assessments. The effect of gradients on stopping distance and brake efficiency requirement. The effect of loading a vehicle. Annexure B - In-service testing of TMMMS (informative) Dynamic brake testing Testing of brakes on brake test ramp

9 Annexure A Safety Figure A.1. Speed versus time graph during braking of a vehicle Apply brakes with foot pedal Start of deceleration Speed Km/h Brake Delay Deceleration due to braking force Vehicle comes to standstill Time (s)

10 Definitions Brake delay (or response time) is the time period from initial actuation of the brake control until the time when 75% of the full brake retardation is reached. Brake efficiency is the mean deceleration from the instant when 75% of the full brake retardation is reached to standstill expressed as a percentage of g (gravity) (for instance, 2,4m/s 2 deceleration = (2,4/9.81)x100 = 24,5% brake efficiency) Brake efficiency = b = a/g

11 Effect of gradient Figure A.2 TMMM on a gradient F 4 = Braking Force Direction of movement F 3 = Normal Force F 1 = Weight ø F 2 = Axial Force

12 Stopping distances on a gradient 140 Stopping distances at 15km/h Brake Efficiency Distance (m) % 15% 20% 25% 30% 35% 40% Angle (degrees)

13 Effect of load on stopping distance Loaded TMMM Direction of movement M 2 M 1 F

14 Effect of load on stopping distance Example A vehicle weighing 8000kg is used to carry a load. The load is 5000kg. The unloaded vehicle was last tested at the workshop and the brake efficiency was 46%. What is the calculated brake efficiency of the loaded vehicle? b 2 = b 1 m 1 /(m 1 +m 2 ) = 46x(8000)/( ) = 28,3%

15 Annexure B - In-service testing of TMMMS (informative) Dynamic brake testing Testing of brakes on brake test ramp

16 Dynamic Testing using Simret Tester

17 Testing on Brake Test Ramp Test ramp requirements. The test ramp should be approximately 4 degrees more than the steepest gradient at the mine. Direction of movement Φ β Test Ramp Length=L Recovery Ramp

18 SANS 1589 Definitions braking system combination of parts that constitute the means of reducing the speed of the TMMM, bringing it to a standstill and holding it stationary. The system consists of a control or controls, means of brake actuation, the brake actuation and the brake components which directly applies a force to oppose movement of the TMMM. Brakes may, for example, be of friction, electrical, hydrostatic or other fluid types, and, if the TMMM is so equipped, the retarder.

19 Definitions service braking primary braking system that is used for controlled application of the service brakes in order to reduce the speed of the TMMM, bring the TMMM to a standstill in normal operating conditions and hold it stationary while the operator maintains the appropriate force on the control. emergency / secondary braking braking function that is used for application of the brakes in order to bring the TMMM to a halt in an emergency situation when there is a failure in the service brake function.

20 Requirements General The following operational systems shall be provided on the TMMM: a) service braking; b) fail safe park braking or fail safe emergency braking or both.

21 Requirements Hydrostatic driven TMMM service braking system Dynamic braking systems for this category of TMMM are permitted as the only service brake system, provided that dual traction/braking circuits are used so that the failure of one circuit, including the bursting of a hose, will not prevent the other circuit from acting as a brake.

22 Service Brake Stopping Distance Requirements Vehicles also traveling on public roads, capable of exceeding 35 km/h Vehicles also traveling on public roads, not capable of exceeding 35 km/h Vehicles not traveling on public roads, with mass less than 32 ton and capable of exceeding 35 km/h Vehicles not traveling on public roads, with mass greater than 32 ton, not capable of exceeding 100 km/h Formula vt v 13x2a with 0,35s delay and 45% efficiency with 0,35s delay and 20% efficiency with 0,35s delay and 28% efficiency with 0,35s delay and 20% efficiency Initial Speed km/h Stopping Distance (m) Stopping Distance (m) Stopping Distance (m) Stopping Distance (m) Sasol Mining (Pty) Ltd Mining Division : copyright

23 Secondary Brake Stopping Distance Requirements Formula vt Initial Speed km/h v 13x2a Secondary Brake Applicable to all TMMM's with 1s delay and 18% efficiency Stopping Distance (m) Service Brake Vehicles also traveling on public roads, not capable of exceeding 35 km/h with 0,35s delay and 20% efficiency Stopping Distance (m) Sasol Mining (Pty) Ltd Mining Division : copyright

24 Requirements (cont ) Brake efficiency The brake efficiency shall be a minimum of 20% (standard requirement for vehicles used on gradients of up to 12,3% (7º) If the vehicle will be used on gradients of more than 12,3%, the minimum brake efficiency shall be specified by the mine to be 8% more than the sine (expressed as %) of the maximum decline angle where the TMMM will be used (see annexure A for explanation).

25 Requirements (cont ) Test gradient The test gradient shall be a sloping surface or tilt platform that is the greater of a) a gradient of at least 20% (standard requirement for vehicles used on gradients of up to 12,3% (7º) or b) If the vehicle will be used on gradients of more than 12,3%, the minimum brake efficiency shall be specified by the mine to be 8% more than the sine (expressed as %) of the maximum decline angle where the TMMM will be used (see annexure A for explanation).

26 Questions?

27 Conclusion The mine shall assess the conditions where the TMMM will be used at the mine and shall prescribe the correct brake performance required for the TMMM at beginning of life and during its service life. In-service testing requirements (informative) has been included in document. The new requirements in SANS 1589 are, in some cases, more strict than ISO 3450.