Jump to content

Clayton Dewandre Hydrovac Brake Servo


Recommended Posts

Hi all...I'm looking for any information I can get hold of regarding these Hydrovac Brake Servos that were made by Clayton Dewandre of Lincoln. I have one that will not work removed from an Alvis Salamander. It would develop a good vacuum, it had been bled through and I could hear and feel the piston moving within the power cylinder, despite this there was none of the normal 'feel' of any servo assistance at the brake pedal. Upon removal and stripping it down there was no obvious signs of any wear and tear; there seemed to be a rather excessive amount of oil in the power cylinder, but this was not as a result of a leak back through the push rod seal. In fact all seals seemed to be in good order with the exception of the cup seal in the hydraulic piston.

 

Could the following be a reason for no servo assistance; if the cup washer/seal in the hydraulic piston was not working efficiently, could, when the engine is running and a vacuum produced, the power cylinder piston move forward under vacuum and push the hydraulic piston forward with no braking effect due to failure of the hydraulic piston seal? (if you get my drift).

 

Anything on this would would be greatly appreciated, as always! Dave

Scampton 29.10.12 012-Optimized.JPG

Scampton 29.10.12 016-Optimized.JPG

Link to post
Share on other sites
  • 7 years later...
23 minutes ago, andym said:

I think that Alvis Stalwart owners might be interested too!

Andy

 

Figure G22.pdf 299.07 kB · 1 download

The only thing to be aware of is that Stalwart brakes use Mineral oil in the hydraulics, whereas most commercial vehicles would be using conventional brake fluid. The seals would have to be suitable for mineral oil.

Link to post
Share on other sites
2 hours ago, Richard Farrant said:

The only thing to be aware of is that Stalwart brakes use Mineral oil in the hydraulics, whereas most commercial vehicles would be using conventional brake fluid. The seals would have to be suitable for mineral oil.

Agreed!

Link to post
Share on other sites
1 hour ago, Dave Jenner said:

Hi Richard how you doing.  I explained that also to the fellow that recently found and acquired his own Mk6...re the mineral oil. 

Hi Dave,

I'm good thanks, still firing on all cylinders! Are you still involved with Steve's museum collection?

Link to post
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...