THE WAY WE WERE - Tapped out and rolling on!

Wednesday, February 13, 2019

After six years in the trade, Paul spent 46 years working for the Ministry of Transport, Commercial Services MOT, VTNZ, Land Transport Safety Authority (LTSA), Land Transport NZ (LTNZ), and then the New Zealand Transport Agency (NZTA).


Photo: Brake rollers under the second steer. The mobile roller tester was huge step up from the Tapley meter, and in general worked well.

Brake testing hasn’t always been the high-tech affair we have today. Some rural truck operators and drivers may recall brake testing carried out in rural areas in the early to mid-90s was conducted via a road test using a decelerometer (or Tapley meter as it was known by some). A relatively small device that was either clamped to the truck or placed in the cab to record braking efficiency or stopping ability of the truck and/or combination. According to the regulations the test had to be undertaken on a “hard, level tarsealed roadway.”

Fully equipped testing stations in those days were using in-ground roller brake testers, and around the mid-90s portable or mobile roller brake testers were introduced into the rural scene, which resulted in a more reliable and consistent brake test regime for both rural and urban environments.
These roller brake testers were transported to rural sites on the back of small trucks. The brake machines were then lifted off, set up and calibrated at the operator’s yard, or rented premises. The introduction of these devices did not always find favour with some operators. Most, however, found them to be an excellent tool in diagnosing inefficient, unbalanced, or poor overall braking performance. As each axle was placed in the roller bed it was weighed automatically and the brake effort and balance recorded (as it still is today), and a pass or fail logged. The system worked well.

One occasion on a first visit to a rural area with the portable brake tester, the operator asked where the little meter was that was usually placed in the cab to test brakes. He was advised that we were moving into the modern age and on this occasion the brakes would be tested using the device sitting at the other end of the yard about 50 metres away. He was asked to move over towards it and wait for instructions. Before another word could be uttered he drove at full speed towards the portable roller brake tester and slammed on the brakes just as the front axle hit the roller bed. After the dust settled it appeared that the truck, a 2-axle Ford D750 of about 12 tonne, had shifted the complete roller bed about two metres across the yard. After fearing the worst and running to the scene, no significant damage was found, however the operator had a large grin on his face. “How’s that for good brakes, mate?” After relocating and a quick recalibration, proper brake tests were performed.


Photo: The Tapley meter was indirectly responsible for random skid marks in many a yard all over the country.

In those days axle tie-downs were not used and a load on the axles improved the chances of a pass. In 2007 all vehicles over 3500kg needed a minimum of 60% legal axle weight, and if that wasn’t achievable, tie-downs were employed to achieve the required load. All the functions to operate the brake tester were carried out from a small handheld remote. These were also a horrendously expensive piece of kit. They were usually put in a safe place at the completion of the brake tests. On numerous occasions when returning to the base station it would be found that the handheld control was still sitting on a ledge/shelf around the area where the last brake test was carried out.

An on-board generator supplied the power to drive the rollers and overall the whole set-up was extremely reliable. The truck utilised in the early days to transport the roller brake tester was a small Daihatsu, which was a little under-powered but did a very reliable job.
A short while after brake testing in this format was introduced in rural areas, the CVIU brought several brake testers themselves for the purpose of roadside brake condition checks between the sixmonthly COF tests.