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

Presented by : Paul SchutteDate: 15 November 2007

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Workgroup

FermelGearratioKomatsuMultibrake NCS Engineering SandvikBell

Prof At von Wielligh – UP (chairman)DMESABSSasol MiningAnglo AmericanAnglo PlatBarloworld EquipmentBhp Billiton



Reasons for Review of SANS 1589

To integrate and review the requirements of the following: SANS 1589ISO 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 1447-1 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



Contents of Presentation

Section added on safety.

Changes in requirements.



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 machinerysurface mining machinery vehicles and machinery used for both surface and underground operations



Trackless Mobile Mining Machines (TMMM)



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.



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 testingTesting of brakes on brake test ramp



Annexure ASafety

Figure A.1. Speed versus time graph during braking of a vehicle

Time (s)

SpeedKm/h

Apply brakes with foot pedal

Brake Delay

Deceleration due to braking force

Start of deceleration

Vehicle comes to standstill



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/s2 deceleration = (2,4/9.81)x100 = 24,5% brake efficiency) Brake efficiency = b = a/g



Effect of gradient

Figure A.2 TMMM on a gradient

F4 = Braking Force

ø F2 = Axial Force

F1 = Weight

F3 = Normal Force

Direction of movement



Stopping distances on a gradient

Stopping distances at 15km/h

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Angle (degrees)

Dis

tanc

e (m

)

10%15%20%25%30%35%40%

Brake Efficiency



Effect of load on stopping distance

Loaded TMMM

F

M1

M2Direction of movement



Effect of load on stopping distance

ExampleA 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?

b2 = b1m1/(m1+m2)= 46x(8000)/(8000+5000)= 28,3%



Annexure B - In-service testing of TMMMS (informative)

Dynamic brake testing

Testing of brakes on brake test ramp



Dynamic Testing using Simret Tester



Testing on Brake Test Ramp

Test ramp requirements.The test ramp should be approximately 4 degrees more than the steepest gradient at the mine.

β Φ

Test Ramp Length=L Recovery Ramp

Direction of movement



SANS 1589 Definitions

braking systemcombination 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.



Definitions

service brakingprimary 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 brakingbraking 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.



Requirements

GeneralThe following operational systems shall be provided on the

TMMM:a) service braking;b) fail safe park braking or fail safe emergency braking or both.



Requirements

Hydrostatic driven TMMM service braking systemDynamic 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.



Service Brake Stopping Distance Requirements

5.94.65.9 3.4 15

Stopping Distance (m)




Initial Speed km/h

9.8 7.5 9.8 5.4 20

with 0,35s delay and 20% efficiency




Formula

Vehicles nottraveling on public roads, with mass greater than 32 ton, not capable of exceeding 100 km/h

Vehicles nottraveling on public roads, with mass less than 32 ton and capable of exceeding 35 km/h

Vehicles also traveling on public roads, not capable of exceeding 35 km/h

Vehicles also traveling on public roads, capable of exceeding 35 km/h

Sasol Mining (Pty) Ltd – Mining Division : copyright

13x2a

2v3.6vt

+



Secondary Brake Stopping Distance Requirements

Service BrakeSecondary Brake

5.9 9.115



Initial Speed km/h

9.8 14.3 20


with 1s delay and 18% efficiency

Formula

Vehicles also traveling on public roads, not capable of exceeding 35 km/h

Applicable to all TMMM's

Sasol Mining (Pty) Ltd – Mining Division : copyright

13x2a

2v3.6vt

+



Requirements (cont…)

Brake efficiencyThe 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).



Requirements (cont…)

Test gradientThe test gradient shall be a sloping surface or tilt platform that is the greater ofa) a gradient of at least 20% (standard requirement for vehicles used on gradients of up to 12,3% (7º) orb) 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).



Questions ?



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.



sans 1589: braking performance of tracklessmobile … 1589- braking performance... · speed versus...

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