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volksjim
Member
| Joined: | Sun Nov 18th, 2007 |
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| Posts: | 104 |
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Posted: Wed Nov 21st, 2007 10:35 pm |
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20mph the way i check them is by road test tapley/bowmonck decelarometer brake test at approx 5mph max
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castrolrob
Trade Member
| Joined: | Sun Sep 10th, 2006 |
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| Posts: | 313 |
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Posted: Mon Nov 12th, 2007 07:45 pm |
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re the landrover,most of them use this layout including range rovers,have not come across any problems assuming a bit of care.footbrake and handbrake testing shud b inertia on 4wd unless your rollers are suitable for 4x4(ours are)as regards your ferret h/brake efforts shud equate roughly to enough to hold on a 1 in 7 hill as this is the maximum permitted on a public road without an alternative route being offered(this cud have changed)find a suitable test station/hill combination and youre in business!as an aside present it at your local vosa test centre-them the guys that came up with the idea of us testing stuff like this,why not give them the benefit of the a**eache that goes with it?
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Wesley
Trade Member
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Posted: Mon Oct 15th, 2007 11:33 pm |
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Hi,
Some Testing Stations have a Plate type Brake Tester, find one of these in Your area and problem solved.
Regards, Wes.
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00EC25
Member
| Joined: | Mon Oct 15th, 2007 |
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| Posts: | 1 |
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Posted: Mon Oct 15th, 2007 05:00 pm |
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I have read the threads re vintage cars with transmission brakes however would welcome the professional's comments in my case relating to 2 vehicles which I own and have had trouble getting tested:
A) Forward Control Landrover 101.
This vehicle has a transmission brake acting on a drum attached to the transferbox rear output shaft only. The examiner asked that I drive at minimum 20mph and apply the handbrake which immediately locked up the rear axle. I was given a pass (no tapley meter used). There is a centre diff in the transfer box between the front and rear output shafts but all the same I was rather concerned about undue stressing of the entire transmission? my question is: can I insist the test is done at a lower speed?
For the foot brake test the examiner insisted it go on a rolling road. The vehicle is permanent 4 wheel drive and the axles have diffs. It survived the rolling road test but as a permanent 4 wheel drive I have been told by other owners such vehicles should never be tested on a rolling road and I risk causing transmission problems in so doing - twisting of prop shafts and/or lifting of shafts within the gear/tansfer boxes. Comments please - should permanent 4 wheel drives be tested on a rolling road at all even if they have diffs?
B) ex military armoured vehicle: 4 wheel drive Ferret armoured car
This vehicle is permanent 4 wheel drive, has no diffs and operates on the basis that the transmission layout is in an H shape. The front and rear wheels on each side are permanently linked on a joint drive so that when the vehicle is raised in the air rotating the front wheel will cause the rear wheel on the same side to rotate and vice versa (rather than the normal front and rear axle configuration). A common maintenance issue is regular transmission wind up if not relased by driving on slippery surfaces.
The handbrake operates the drums at each wheel station via cable linkages.
For the handbrake test the examiner (using a tapley meter) required me to drive at 20 - 25 mph and apply the handbrake. These are relatively heavy vehicles (approx 4 tons) and do bleed speed very rapidly under engine braking. It is likely therefore that at slow speeds the vehicle may have almost stopped of its own accord before I have physically completed the handbrake application.
The examiner had great difficulty in getting a reading from the tapley meter because the vehicle slowed gently over a reasonable stopping distance and did not jerk to a stop. In addition to the vehicle inertia described above, it is also physically difficult to pull the handbrake on suddenly (it is a very contorted procedure to reach the handbrake when driving unless you have long arms that would otherwise drag on the floor when walking upright!). I think he let it go with a reading of 49% which we decided was the average of the 5 times I tried the manoeuvre before he gave up. Comments please - is there a better way of doing the handbrake test? (obviously can't go on a rolling road)
As the braking test can only be carried out using a tapley meter, and I take very seriously my duty to ensure that I am driving a road safe vehicle, can anyone suggest a way of testing the braking performance of each wheel since the tapley meter can't tell you this. Ex army mechanics I have spoken to simply suggest drive it fast enough to leave skid marks and make sure there are 4 of them which all start in the same place and that the vehicle stops in a straight(ish) line. Anyone think of a different way to do it?
PS - footbrake test is not an issue as they are servo assisted and I can stop the vehicle with a nice big jerk to register on the tapley. Indeed the first time he did it the meter simply fell off the vehicle because he had balanced it on the hull armour rather than securing it in place.
Footnote - these vehicles were designed in the late 1940's / early 1950's and the technology is obviously of that age. Mine was built in 1965 and is not exempt (although owners of pre 1960 builds do claim exemption using all sorts of clauses: motor tractor or HGV pre 1960 >3.5 tonnes being the most common two used)
Thanks in advance
John
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