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rolling roads


craig
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this has been discussed before, if done with transfer box in neutral & at no more than 10mph, the rollers drive the wheels, engine is only running to provide vacuum for the brake servo during the test, my 110 has always had it's MOT brake test done on a 2 roller rig, never caused me any concern.

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4x4s should never get tested on anything otyher than a 4 wheel rolling road.

when we test 4x4s we have a special box thing with an inclinometer typething in it which shows the braking power when you brake.

this is mot standard

so why do LR take the trouble to add the notes attached above ?

if done on a 2 roller rig with care there is no problem.

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handbrake isnt meant to be applied whilst moving-its a transmission/parking brake, the MOT guy should find a hill and make sure the 'handbrake' holds the truck on it.

The problem is driving one wheel with the brake tester drum-say for example the rear axle, turns the diff crownwheel which in turn rotates the pinion at a fair higher speed than the half shaft is turning at (3.4odd or whatever the diff ratio is times quicker). This then turns one half of the centre diff-which because the front half of the diff is stationary means the small planet gears in the centre diff are now moving at quite a lick which could involve them seizing. IIRC.

I was livid last MOT when the guy said he'd Tapley it then stuck it on the rollers.

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Edit: Whoops, I didn't read the bit at the end...which reads:

This test may be conducted as an alternative to a decelerometer test on certain large vehicles with a dual circuit braking system (min. 16% efficiency required) such as Motor Caravans fitted with a prop shaft brake not suitable to be tested on a roller brake tester.

Care should be taken to avoid any risk of ‘grounding’ the vehicle when reversing onto and driving off the test slope.

D. Parking Brake Gradient Test

1. Reverse the vehicle onto a 16% gradient, apply the parking brake and release power assistance

Note: When the parking brake is being tested by the gradient test, the service brake (foot-brake) may be used to assist in setting the parking brake

My mistake, you were correct. Will be having a word with my garage then! They told me it had to be tested while moving!

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my garage stuck it on a 2 roller rolling road at quite a lick of pace then pulled the handbrake. it jolted the car forwards and off of the rollers. after nearly dying he wasnt my favourite person in the whole world and boy did he find that out when he had the cheek to tell me it only just passed at 17%.

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If a Land Rover fitted with an LT230 transfer box is tested on MOT 2 wheel brake rollers, the item put under load is the centre diff, putting the t/box in neutral will NOT make any difference.

The speed at which the brake rollers run at should not harm a centre diff in good condition. However...if there is any fault or weakness in the diff it may cause a failure, if this occured the testing station would be liable for the damage.

The transmission brake in good working order along with the prop and rear axle are perfectly capable of stopping a Land Rover at the low speeds of a roller or decellerometer test. However once again, if there is an unseen weakness anywhere there is potential for damage and the test station would be liable.

For these reasons I never test Land Rover brakes on rollers or transmission brakes in motion. But that is not to say it can't be done, the advice from VOSA and my personal opinion is to be on the side of caution.

My advice is to always get your Land Rover tested at a Garage that is familiar with them and tests plenty of them. Ask to speak to the tester about how they'll test the brakes and express any concerns you have.

You know the history of your vehicle and how you use it, get the brakes tested accordingly.

Hope that clears it up.

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  • 4 months later...

Hi

Can anyone point me in the direction of the MOT testers hand book with reference to brake testing, the use of caution regarding propshaft handbrakes and rolling roads on 4x4's. Page numbers, item numbers or links I can copy.

I have just taken one of my 110's to the test station I have been using for years to find it had changed hands, I was short on time and had to get it tested as its MOT is due, they then proceeded to test the rear wheels on a 2 wheel rolling road. My landy's have in the past always been tested using a tapley meter using the drive along the road and brake method.

The main front to rear brake pipe/line left go during the test failing the car and not completing the brake test.

Vehicle is a 1999 110 300TDI

I'm going to replace the line and a couple of the others while I'm at it however can I request a tapley meter test rather than the rolling road ?

Many thanks

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