[AT] hydraulics question

[Cecil E Monson]

>  Dudley
> 	I've got to take issue with a couple of your statements above.
> 	A hydraulic control valve relies on the fine clearances achieved
> 	at manufacture to perform. To hone a valve body is going to only
> 	increase internal leakage unless one is in a position to fit 
> 	oversized spools. O rings are fitted to prevent low pressure
> 	external leakage as there is generally a gallery back to the return
> 	inboard of the O rings.
> 
> 	Secondly, oil supply to the cylinders is common, therefore if one
> 	leaks internally the drop in load gets shared between them.
> 	Otherwise, to maintain equality in stroke length, there	have to be
> 	flow dividers in their supply circuits to ensure balanced flow to the 
> 	cylinders.
> 
>  Cecil
> 	With the problem at hand, water contamination most probably has
> 	contributed to the deterioration of the seals. If the original type
> 	seals aren't available, there are quite a few manufactures that can
> 	supply synthetic seals of more modern design that will either fit
> 	in the original locations or can be fitted with the remachining of
> 	the pistons. I've found it hard to go past Greene Tweed seals in
> 	when rebuilding & modifying cylinders.
> 
>  Tom

	Thanks, Tom. I'll keep that in mind also.  As to Dudley's comment
on honing and polishing, I took it to mean he polished and honed the cylinders
and pistons, not the inside of the control valve. Read his post with that in
mind and I think you will agree.

Cecil
-- 
The nicest thing about telling the truth is you never have to wonder
what you said.

Cecil E Monson
Lucille Hand-Monson
Mountainville, New York   Just a little east of the North Pole

Allis Chalmers tractors and equipment

Free advice