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Bedford MJ Brake Test MOT


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Bedford Mj due for test next month.

Local vosa station now closed,new independent ATF does not have a hydraulic jacking/load beam,so with now have to take truck with approx.3 ton load on board for load sensing valve brake test.(65 percent of 5.5 axle rating)

The problem is that the MJ is down rated to 7.5 Ton (Rear springs cut)so not sure if suspension will take the weight,not to mention headlight beam check with front end up.

Any ideas anyone ?

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I agree with you Tony, new weights should be on the new plate issued when it was downrated.

Thanks fellas but new vosa plate cert.still showing 5 ton rear axle load and I think to put around 3 ton on is just going to be too much for the Springs I will contact vosa to see if I can get the spec.altered on plating cert.

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Some places will let you tie the load sensing valve up for the test as long as you release it before you go back on the road. Not sure if that will help you but it's how we got a box-body RB44 to pass as there was nowhere practical to put weight.

 

Thanks for that I will ask visa if possible to do that,as sounds a good idea.:-)

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Caution! the vehicle MUST be loaded with the correct weights otherwise it will not pass its braking tests due to the rolling road weighing the axles and calculates what braking force it should be..

I know as i just mot'd my daf drops without weight on it and tying up the brake compensator and it failed!

The actual brake test passed! but failed because it had not enough weight on the axles..

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Thanks for that,interesting to know that the rolling road also checks axle weight,so perhaps better to be over the 65 percent than under weight.

still think that the rear axle plated weight should have been altered when springs cut etc.

Will try and speak to someone at VOSA today !

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When you say rear springs have been cut - do you mean the helper leaf has been cut off each side of the centre clamp? The normal method of downplating is to remove the helper spring brackets which has the same effect of course.

 

I doubt if 3t would put the springs down onto the helper springs (no, correction - Bedford rear springs tire very easily so may have lost their shape somewhat :D).

 

I think I have a Ministry plate on a civvy MJR at work - will try to get a pic today.

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Ask them to do a Tapley test instead of rolling road test.

 

That reminds me of doing high speed braking development at MIRA....

 

We used to use Tapley meter when I was a mechanic for kit cars that were too light to stop the rolling road rollers, or for three wheelers.

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Bedford Mj due for test next month.

Local vosa station now closed,new independent ATF does not have a hydraulic jacking/load beam,so with now have to take truck with approx.3 ton load on board for load sensing valve brake test.(65 percent of 5.5 axle rating)

The problem is that the MJ is down rated to 7.5 Ton (Rear springs cut)so not sure if suspension will take the weight,not to mention headlight beam check with front end up.

Any ideas anyone ?

 

Hi , we just put my RB44 through a test at an ATF , the RBT was a new one I am told that a code is input by the tester which sets the machine to the individual requirement of your truck. This should be the same as the last test unless the truck has been down rated since then, in which case a new code should be applied .The rollers automatically weigh check the axle weights and the test can be carried out . We tested with no load didn't tie the compensator and achieved lock out on front and rear axles and put the fear of god into the tester when the handbrake was applied and the RB attempted to jump out the rollers ! . I think it is down to you or the test station having the correct code for the RBT which is only available from VOSA technical. Hope this helps Alan

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Sorry can't find the plate - I took it out of the old cab when it received a TL cab, filed it 'somewhere safe' :nut:

 

This is just my thinking here (difficult to be precise without seeing the plating certificate):

 

The payload within the body under max plating of your truck should be around 4.5t, (as a comparison the body plus payload capacity is 5.914t and the body weighs around 1.5t) - which means 65% laden would be 2.95t.

 

So the request for loading of 3t giving 65% payload sounds about right. But this should be evenly distributed in the body therefore rear axle would only be taking around 2/3rds of that - say 2 tonnes. No way will the springs be a problem at that loading.

 

But is this specifically what the test station wants? Or has it asked for 3T over the rear axle? Seems to me 3t over rear axle is equivalent to 65% of the un-derated load?

 

 

Edit: They seem to be asking for 65% of the original rating, not the derated rating - so it seems the plating information has not been amended in their records? If the truck is derated to 7.5t the payload would be around 2.3t (chassis 3.9t plus body est 1.5t), so 65% of loading would be 1.5t.....

Edited by N.O.S.
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