Jump to content

Alvis Salamander Brakes and Hydraulic oils


Dave Jenner

Recommended Posts

Good morning all

 

I'm just after some idea's and opinions if possible.

 

The Alvis Salamander (RAF Mk6) I think I'm correct in saying, braking system differs from it's brothers the Saladin, Stalwart and Saracen, so I believe anyway! Although I think it may share some common components. The Salamander has a 2" lockheed master cylinder at the front end, in the engine bay a hydrovac brake servo and standard drum brakes and wheel cylinders set up.

 

The master cylinder was replaced just over a year ago. We had managed to 'procure' OM11 which is a high grade mineral oil and replaced OM13 in service (the recommended oil type) quite some time ago. All was well for almost 4 months and then the brake cylinder started to play up with the piston sticking in the cylinder. This progressively worsened until it appeared to stick completely. It was removed from the vehicle yesterday and the piston is stuck fast within the barrel.

 

It without doubt appears that a reaction to the oil has occurred causing one of the two cup seals on the piston to have broken down. One of these seals is a standard looking type rubber seal, the other is much stiffer and appears to be made from some fibrous compound. I cant actually tell which seal may have reacted as it's stuck fast!

 

In the RAF OM11 replaced OM13 and according to the data we saw did seem to suggest it was suitable, but I cannot think of any other reason for the cylinder to fail except for a reaction on one or both the seals from the oil.

 

If anyone has any thoughts, apart from "should have used OM13" :cool2: I would like to hear from you.

 

Cheers Dave

Edited by Dave Jenner
Link to comment
Share on other sites

Just as a thought - where did the master cylinder come from Dave? Original or replacement?? AFAIK all the FV6xx series used the OM10/11/13 oils for braking systems so is it possible you had the wrong seals in the cylinder?????

If it were the wrong oil I would have expected problems right through the system including the wheel pistons........

Link to comment
Share on other sites

Just as a thought - where did the master cylinder come from Dave? Original or replacement?? AFAIK all the FV6xx series used the OM10/11/13 oils for braking systems so is it possible you had the wrong seals in the cylinder?????

If it were the wrong oil I would have expected problems right through the system including the wheel pistons........

 

 

Hi Neil, thanks for that. The replacement cylinder originated from Alvis. It had been in storage with all the original wrapping on it before it was passed onto me. I'm hoping that just the MC has been affected, apart from the slowy worsening failure to return symptom, there was no sign of a problem with either the servo cylinder or any wheel cylinders. I'm hoping I might have had those start to stick and either lost braking effort or had binding brakes, which there was no sign of. So your saying that the OM11 should have been OK?

 

I don't know how much of the 'wrong type' of oil would be needed to destroy a seal. The vehicle had been without brakes for many years and when I first took the original cylinder out the seals were destroyed and oil had leaked into the boot. How much oil would it take to damage a seal? I wondering that if some wrong oil had previously been used to top up, whether some was still in the feed and was sufficient to cause damage.

 

Dave

Link to comment
Share on other sites

AFAIK all the FV6xx series used the OM10/11/13 oils for braking systems ....

 

Neil,

I do not know where you got the information from about the use of OM10 and OM11 in braking system of FV600 series vehicles. For starters there was no OM10 listed in inventory of lubricants to the Armed Forces in the 1963 nor 1991 lubricants handbook. OM11 was a lubricating oil for early types of aircraft turbo jet engines and Rover gas turbines, also an inhibitor for fuel systems in stored aircraft. In all the years experience working on Stalwarts, Saladins and Saracens whilst in service the use of OM11 has never come up. Also it is only Salamander and Stalwart that have master cylinders, the two armoured vehicles have a completely different type of hydraulic system. Some very early Saracens used a slightly heavier viscosity hydraulic fluid, but that has nothing to do with the case in question.

Link to comment
Share on other sites

Neil,

I do not know where you got the information from about the use of OM10 and OM11 in braking system of FV600 series vehicles. For starters there was no OM10 listed in inventory of lubricants to the Armed Forces in the 1963 nor 1991 lubricants handbook. OM11 was a lubricating oil for early types of aircraft turbo jet engines and Rover gas turbines, also an inhibitor for fuel systems in stored aircraft. In all the years experience working on Stalwarts, Saladins and Saracens whilst in service the use of OM11 has never come up. Also it is only Salamander and Stalwart that have master cylinders, the two armoured vehicles have a completely different type of hydraulic system. Some very early Saracens used a slightly heavier viscosity hydraulic fluid, but that has nothing to do with the case in question.

 

Yes - my goof there Richard - teach me to read forums when tired - apologies to all for that...... :red: :red:

Mixing up OM numbers with SAE numbers and order numbers - doh!!!!!! :red: :red:

Link to comment
Share on other sites

I think it was my own goof! :nut:

 

One of the piston seals I used last year in re-building the master cylinder was newly acquired and I now think it modern enough to be made from a synthetic material and not natural rubber as in original 1950/60 specs. This then reacted to the petroleum based OM11. Why do I think this? Well I now have the piston out of the cylinder and it's swollen by about 20% of it's original size!

 

Lesson learnt! (At least I hope so!)

Link to comment
Share on other sites

I think it was my own goof! :nut:

 

One of the piston seals I used last year in re-building the master cylinder was newly acquired and I now think it modern enough to be made from a synthetic material and not natural rubber as in original 1950/60 specs. This then reacted to the petroleum based OM11. Why do I think this? Well I now have the piston out of the cylinder and it's swollen by about 20% of it's original size!

 

Lesson learnt! (At least I hope so!)

 

Hi Dave,

Now you have discovered which seal was causing the problem, I am pretty certain that the seal you used was on for normal synthetic brake fluid. You should be looking for those made for mineral oil use specifically. I came across this once when working for the army, there was one type of Ferret (Mk4) that used OM13 mineral oil in the brakes as they were disc type. All the Mk1 and 2 Ferrets were drum brakes an used a normal brake fluid. Someone at a Unit which had both versions got confused and put the wrong fluid in one of them. This swelled the seals like you have found and when I stripped the cylinder the seal was half as big again. A test for you would be to get a seal and leave it in a jar of oil for a day or so, if it has not expended then it is OK. They do not appear to be marked as to what fluid they are for.

 

I will return you email later on, thanks

 

regards, Richard

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...