Centurion shock absorber question

[David Herbert]

Actually the flat topped 'button head' nipples that accept a grease gun fitting that slides on from the side are an American design, originally made in the USA by Alemite, as Rob has said. They were used in plant applications (most wartime crawlers and scraper boxes for example) and came in two head sizes and many thread sizes. These were referred to as Small TAT and Big TAT I believe, but possibly only in the UK. They were adopted by the MOD as standard and are still available commercially here in the UK.

David

[Mike Cecil]

Hi Malcolm, yes, I think you are right: conversion to grease was the road wheels axle arms, not the shock absorbers: sorry to mislead you.

The 1973 Aust EMEI Data sheet for Centurion lists shock absorbers, each reservoir, as 4 gallons of 0-134 (OM-13) oil (sounds too much? Maybe 4 gallons covers all the shocks and that is a typo?) and axle arms as XG-274 grease.

OM-13 is listed as 'lubricating oil, general purpose, petroleum, light' with a viscosity of 13 @ 38 degrees C.

XG-274: I don't have a spec for, but XG-276 is a moly grease with extreme pressure additives, and XG-279 is a general purpose automotive and artillery grease. XG-279 sounds closer to the mark.

I also looked at the maintenance book, and the shocks, when serviced off the vehicle, are filled using a special jig that works the shock back and forth to pull the oil into it. They are then topped off and the plug inserted before assembling back into the suspension unit.

Regards

Mike

[Tony Smith]

Originally Posted by Mike Cecil

The 1973 Aust EMEI Data sheet for Centurion lists ...... axle arms as XG-274 grease.

XG-274: I don't have a spec for, but XG-276 is a moly grease with extreme pressure additives, and XG-279 is a general purpose automotive and artillery grease. XG-279 sounds closer to the mark.

Mike

XG-274 is still a General Purpose Grease (I got a tin of it when I bought my Perentie Land Rover), manufactured by Shell as an Aviation grease. Specs are listed by Shell HERE.

[Malcolm Towrie]

David, thanks for the information. I stand corrected. I thought these fittings were obsolete but I see Amazon is still happy to sell me all types of them!

Mike, I suspect the 4 gallons per suspension unit is correct. Each unit is about 3 feet long, about 10" wide and the shock absorber section at the top is about 6" deep, which works out to be a volume of about 8 gallons. I'm reluctant to commit 16 gallons of oil to the 4 suspension units that have shocks without being sure that it's doing something useful. According to our expert here, the T-54 didn't have shocks either. So did they go out of fashion after the war?

What puzzles me is if you neglect the shocks because they are not effective, what happens when they'd seize up?
Malcolm

[Mike Cecil]

Tony,

I put a thank you up for the grease info yesterday, but it seems to have evaporated (must have hit the wrong key!)

So... thank you. All adds to what we know.

Malcolm, 4 gallons each: that's going to be expensive, but better to put at least some oil in each, I'd suggest. You are not going to war in it, so enough oil for the very limited use it will be subjected to, ie just enough to prevent seizing.

Mike

[Grant Bowker]

Originally Posted by Malcolm Towrie

What puzzles me is if you neglect the shocks because they are not effective, what happens when they'd seize up?

To my mind, there is a huge difference between a shock that is moving but not absorbing much shock and a unit that is behaving more or less as a solid steel rod (seized). As stated above, enough oil to stop it becoming solid would seem to be good.

[Malcolm Towrie]

I agree, I'll fill up the reservoirs. The spec'd OM-13 is a very thin hydraulic oil, with an ISO viscosity of 12-13 cS. These lighter oils are expensive, so I think I'll use the common ISO 32 hydraulic oil. I can get 20 litres for $50, so about $200 total. That's no problem. And we'll only be out $200 if it all leaks out.


Malcolm