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Source: Farmers Weekly post
SUTTON, U.K. – About three-quarters of trailers with hydraulic brakes fail dealer tests while a quarter of these offer no stopping power whatsoever.
Often put on a pedestal as the answer to all our hydraulic braking issues, air-activated anchors have an equally poor track record – most of which is down to a lack of maintenance and adjustment.
A few simple things can be done to assess the problem and tweak trailer brakes to get them up to speed.
We got some advice from Dave White, service manager at Lincolnshire trailer sales and hire specialist Ireland’s Farm Machinery.
Related post:
Trailer Brake Controllers Are More Important Than You Think
He looks at how to test your hydraulic brakes, upgrading, parts and costs.
In White’s experience many brakes fail to comply with safety standards.
He says: “When we started out with Bagma’s brake-testing kit we found that nearly all trailers running on standard ag-spec eight-stud axles were failing to achieve the minimum 25 percent braking efficiency.
“And with air brakes it’s often worse as they need to reach 45 percent efficiency. Like many farm trailers, our hire fleet is stood still for much of the year and so drums can soon rust up through lack of use.
“We need to know for sure that the trailers are up to scratch before they go out and so we’ve got a fairly straightforward procedure we go through to get them ready for the road.”
Pre-testing prep
Before anything goes through the Bagma tests at Ireland’s, the brakes are checked for adjustment and slack-adjusters are wound up or splined levers wound round and repositioned on their shafts.
The test
Bagma and Turnkey have jointly developed a brake tester that requires no special kit to operate other than the simple BrakeSafe box, plonked on the floor of the tractor cab.
Effectively a decelerometer, it measures the forces that come into play when the anchors are applied.
By plumbing the trailer brake line into a spool valve, it is possible to measure the braking efficiency of that trailer, independent of the tractor.
The oil jetting out of a spool valve is typically at much higher pressure than what comes down the brake lines, so a restrictor valve and pressure gauge are used to provide a more realistic braking force.
With the brakes plumbed up and the tester box in the cab, it’s then simply a case of setting off at a steady pace (target speed of about 30kph), using the hand throttle to keep engine revs at a steady 1,800rpm, therefore maintaining an even oil pressure.
Once up to speed, the driver then dips the clutch and pulls the spool lever, bringing the whole rig to an eventual halt. It is noticeably slower than normal without the aid of the tractor’s brakes.
Down in the footwell, in a series of whirrs and bleeps, the BrakeSafe box does its calculations and then comes up with a figure for braking efficiency and spews out a supermarket receipt-sized printout to prove it.
To get a true figure for that trailer’s stopping power some more calculations are needed to take the weight of the load into account. That way if the trailer is not loaded up to the max it is still possible to generate an accurate picture of just how well it would stop if it were.
Finally, a percentage figure for braking efficiency is generated – trailers with oil-activated anchors must come in above 25 percent, while air-braked rigs must achieve 45 percent.
The entire post, with images, can be viewed by clicking HERE.
