2 ton Benford Dumper with binding brakes

[Richard Thorp]

I have a 1983 2 ton Benford Dumper, with a brake problem

the brakes seem to bind after driving half a mile or thereabouts. After resting, they free up, but then after another short distance they bind again. The brakes are fully enclosed in the axle and I can see no adjustment. The brake pipes are not kinked, and the master cylinder seems free. I have also bled the brakes fully, and there seems to be no obstruction that stops fluid flowing back to the master cylinder after pressing the brake pedal.

Can anyone offer a little guidance on what I should investigate further?

many thanks
Richard

[essexpete]

Has it got handbrake levers coming out of centre area of the axle (below the brake pipe entry). Just asking because sometimes if the handbrake is not totally free you may get this sort of symptom. Could be the handbrake cable wrongly adjusted or partially seized.

Another possibility could be breakdown of flexible hose (assuming you have a pivot steer) that allow fluid to move under pressure but not return.

[Richard Thorp]

ah, I will look again closely at the flexible hose, thanks.

It is definitely not the handbrake. I can turn this freely by hand, and also, I notice the axle hubs getting slightly warm

-R

[Paul Henson]

Hi
Did you resolve the problem as I have the same symptoms and think it maybe the oil seals gone
Cheers
Paul

[Richard Thorp]

Paul

Yes. The master cylinder seemed free, but when I dismantled it closely, there was some corrosion in the mouth of the cylinder under the boot. This meant that the outer piston that operated the front brakes would not retract fully. This last few mm of retract travel is needed to uncover the port to the reservoir that bleeds off excess fluid from thermal expansion, so what was happening was after a couple of uses, the brakes would bind a little, then get hotter, bind more and so on.

I stripped and cleaned the cylinder up, and they work well now. The seals were not obtainable, so I took a risk and rebuilt the cylinder with the old ones.

cheers
R

[Paul Henson]

Thanks Richard.
I have replaced seals on the drums and transfer box as they were leaking and now have taken off the brake master cylinder.
It is in a terrible mess so I will hunt for a replacement.
Just realized I can use the dumper with no brakes,,,just need to take a little more care

[partsman]

have you checked the oil in the axle?
The brakes are immersed in oil and it could either be low on oil or have the wrong oil in it.
Should be a Wet Brake Lube, or Super Universal Tractor Oil.
As for the master cylinders, I have these in stock here.

mail me on graham@hpsnet.co.uk