Re: Bendix Treadle Vac Study- Serioius Business!!

Posted by HH56 On 2011/1/6 20:58:46

In addition to the large return spring, there are some springs, diaphragm and a tilt lever assy inside the power piston. If all is moving there freely, releasing the pedal will allow the inner piston spring to work that mechanism, closing the vacuum poppet to the apply side and opening atmosphere to both sides. Assuming nothing has prevented that, even though the power piston might stick or not retract all the way, there being no force applied on pedal should keep all in a state of normal relaxed atmosphere going to both sides of piston. The bigger issue would be if piston had not retracted all the way to the last 1/4 or so inch of travel, compensator valve might not tip and fluid would be trapped. Heat and expanding fluid could cause the brakes to drag or apply. The vacuum sucking the fluid out seems to be the result of that reservoir gasket not allowing for any relief opening.