another brake question

[grumpy6711]

hi folks
just got around to changing the Right Hand brake on my 6711 and before i put it back together I have two questions-

1. In the workshop manual the leading shoe and trailing shoe have slightly different profiles.The shoes coming off, both the leading and trailing shoe are identical to each other. One of the shoes is broken. The new ones to go on are also a matched pair (and they are the same as those coming off).

So has the design changed slightly over the years and it is correct that they be a matching pair??

... or should there be a leading shoe and a trailing shoe and this is possibly why it broke in the first place??
As far as i can see the 'shops' only list 1 RH shoe and 1LH.

question 2 - regarding the slave cylinder.
The bleed valve comes out at the opposite angle to the one coming off, but as far as i can see will still fit and be adjustable when in situ.

Is this correct?? or have i been sent the wrong side?

There are pictures of the old and new here.... https://www.dropbox.com/sh/rok652hrfcc1t4l/X1RL4FLwle


thanks in advance
nev

 

[Renze]

If you take off the dust boot and measure, both sides have equal diameter pistons.. And the shoes, i never saw any difference, when i buy them they come in shrink wraps packed by the four..

All of them are still happy running, even when braking 20t combinations...

 

[grumpy6711]

so in the pack of four they are all the same??

 

[hve]

Hi Grumpy, Pictures all look ok to me, ........... on a car the trailing end of both shoes has the lining cut back 20-30mm (heal) and the leading edge of the shoe on the leading shoe only has the lining cut back 10-20mm also.
However the Zetor setup is the same as a Truck with S cam opperated Airbrakes with fixed pivot points and not self aligning. so there is no leading or trailing shoe....... as you want the brakes to work equally well in reverse and forwards. (remember only one shoe (leading Shoe) does any real work in each direction of travel with this design).

 

[grumpy6711]

cheers guys. mind at rest
back to the spanners!

 

[ixer0]

Hi,

Re the bleed valve angle. Assuming the correct cylinder was fitted originally, then the one you've been given is for the other side of the tractor. They are not interchangeable. If you get round the different pipe fitting angle there is a difference inside the cylinder. Under the rubber dirt seal you will find a red paint mark on the piston going to the leading shoe. The difference is in the distance the piston can retract when you let the brake off, it's only 0.5 mm but can make the brake drag. I see no reason why you can't swap the pistons from end to end if it is wrong.

Mike

 

[grumpy6711]

Thanks Mike,
if only you'd posted a little earlier. > portal is now back on, just waiting for a new brake pipe.
I double checked the packaging and it says its the right hand one. and i think the box was sealed when i got it, so fingers crossed the wrong one had been put on before. ???
I would take it all apart again but my 'engine hoist' has driven away again. (FEL on another tractor) .
i will have a check tomorrow which way the the valve is pointing, towards the front or rear of the tractor. according to the pic i think it should be facing front???

 

[grumpy6711]

.... i will have a check tomorrow which way the the valve is pointing, towards the front or rear of the tractor. according to the pic i think it should be facing front???

well it faces the rear of the tractor and is behind the brake pipe connection which sort of makes sense.
the uninterfered with LH side also faces rear so is the opposite of the new one which is good. i hope

 

[grumpy6711]

Update:
Eventually my new brake pipe arrived, 4 weeks after ordering (well to be honest 3 1/2 weeks waiting for one dealer, then cancelled and ordered from someone else which arrived within 48hrs!)
All went together easily and lined up so i guess it was the correct side cylinder. a couple of yards back and forth and its a good 'un.
now the two skidmarks are on the road! and not one on the road and one in me pants .
Thanks for help and advice guys.
cheers
nev

 

[hve]

Good news Nev,
Thanks for posting the update.