David Brown 995 - Seals on Clutch & Braking System

pakalasa

I have an old 'David Brown 995' from around 1976.
These have a raised cab which meant that the clutch and brakes were lifted up also using a closed hydraulic system. Same system for both clutch and brakes.I have a shop manual but it doesn't cover this sytem because it was a later conversion.

I am getting constant trouble with the seals on the hydraulics leaking. It's only a year since I replaced them and they are leaking again.

My local Case guy says that either standard mineral based hydraulic fluid or LHM (expensive) is fine.

Anyone have any ideas?
When I took out the old seals, it looked like they they had softened up from the oil. But I'm not sure.:(

snowman707

No.. mineral oil is not suitable for either the slave or master cylinder, original case/db recommended shell tellus 27, however it is difficult to source same today.

Hydraulic fluid is the best alternative

you will need to replace the seals again as they are now ruined from the mineral oil. thoroughly check the inside of the cylinder for any scores(scratches) or rust damage. thoroughly clean & you will need to get a new 1 if damaged otherwise the seals will go again

atkins in cork youst to stock these kits,

powerfarmer

Recently came across this site, David Brown tractor club loads of DB info:
http://www.dbtc.co.uk/index.php

pakalasa

Guys, thanks for the replies.

Ya, "shell tellus 27" is written on the oil reservoir caps.

This is the oil I used;

ULTRAMAX 46
Mineral oil based hydraulic
oil meeting DIN 51524
Part 2 Specification.

This is made by Exol Lubricants.
I bought it in a motorfactors, they told me is was standard hydraulic oil.

Snowman707 - is not all regular hydraulic oil mineral based?

snowman707

pakalasa wrote: »

Snowman707 - is not all regular hydraulic oil mineral based?

You have me there: o:o:o:o:o

maybe so but I think mineral oil as we know it is petroleum based.

am open to correction here

we had an 995 like u & some genius put green mineral into the master cylinder, like ur story seals didnt last very long.

as I said earlier waste of time putting the seals if the cylinder is not pefect

marlyman

You must use LHM. This is the only fluid that works in these systems.

pakalasa

marlyman wrote: »

You must use LHM. This is the only fluid that works in these systems.

Great Stuff.
There must be some additives in the regular hydraulic oil that attacks the seals.
Any idea what material is in the seals?


Apparently Citroen developed LHM for use in their suspension system. They used vegetable oil originally.

"In August 1967, Citroën introduced a new mineral oil-based fluid liquide hydraulique minéral (LHM). This fluid was much less harsh on the system, and remains in use to the present day."
http://en.wikipedia.org/wiki/Citro%C3%ABn_DS#Suspension

marlyman

its the opposite, there is exra additives in LHM to protect the seals.

snowman707

pakalasa wrote: »

Great Stuff.
There must be some additives in the regular hydraulic oil that attacks the seals.
Any idea what material is in the seals?


Apparently Citroen developed LHM for use in their suspension system. They used vegetable oil originally.

"In August 1967, Citroën introduced a new mineral oil-based fluid liquide hydraulique minéral (LHM). This fluid was much less harsh on the system, and remains in use to the present day."
http://en.wikipedia.org/wiki/Citro%C3%ABn_DS#Suspension

What colour rubber are the seals? Black or Green?

pakalasa

Green !!!!!!! The outer bellows is black though, but that is only a cover.
Why?

snowman707

I have used them(green), & found them trouble some reverted to the black ones & used hydraulic oil with no problems.