Re: Brake issues
Posted by HH56 On 2023/6/14 16:32:52
Kev is probably correct in that the compensator valve is suspect if the brakes fail at times and then work again. This is a critical valve and consists of a spring held single piece of rubber that the end of the ram or piston bumps against in the released position and normally holds slightly tilted and open so fluid can freely enter and leave the pressure side. When the pedal is pushed and ram or piston moves forward to displace the fluid, the spring can then pull the rubber straight and upward so valve seals the port. The increased hydraulic pressure in the master will force it tightly closed as long as there is a good seal to start with.
If the spring is weak or if there is any kind of contamination, old congealed or crystalized fluid or anything else floating in the fluid that happens to land on the seat as the valve is closing the seal is lost and there will usually be no brakes because whatever hydraulic pressure is being generated in the master just pushes fluid back into the reservoir and not out to the wheels. When the pedal goes back to the released position and the valve opens again the debris might move off the port so the next time you apply the brakes everything works fine. This action has resulted in the bad name Treadlevacs have of stopping at one light but not the next.
If the system has not been flushed for awhile I would carefully examine the condition of the fluid to see if this could be your problem. The debris might not even be seen because it could be floating in the piston side below the valve and not in the reservoir. Even better would be a rebuild particularly if the unit has been sitting and is now being placed back in service.
Here is a page from the Easamatic Training Manual. This book was written when your 52 unit was used which has a slightly different power or vacuum operation than later units. You can download the manual from the literature section and photos are much better than those in the 51-4 service manual.
Attach file:
compensator valve.jpg (302.80 KB)
If the spring is weak or if there is any kind of contamination, old congealed or crystalized fluid or anything else floating in the fluid that happens to land on the seat as the valve is closing the seal is lost and there will usually be no brakes because whatever hydraulic pressure is being generated in the master just pushes fluid back into the reservoir and not out to the wheels. When the pedal goes back to the released position and the valve opens again the debris might move off the port so the next time you apply the brakes everything works fine. This action has resulted in the bad name Treadlevacs have of stopping at one light but not the next.
If the system has not been flushed for awhile I would carefully examine the condition of the fluid to see if this could be your problem. The debris might not even be seen because it could be floating in the piston side below the valve and not in the reservoir. Even better would be a rebuild particularly if the unit has been sitting and is now being placed back in service.
Here is a page from the Easamatic Training Manual. This book was written when your 52 unit was used which has a slightly different power or vacuum operation than later units. You can download the manual from the literature section and photos are much better than those in the 51-4 service manual.
Attach file:
compensator valve.jpg (302.80 KB)
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=258068