Re: 1956 Four-Hundred Brake Master Cylinder

Posted by HH56 On 2024/6/9 15:20:17

Believe it or not, power brakes while supposedly standard on senior models like the 400 were often not wanted by the buyer and omitted. Actually just about any of the "standard" power items could be omitted and a manual version factory installed if the customer ordered it that way. Supposedly Packard was the only luxury car maker at the time that would do this.

Starting in 52 Packard offered the Bendix TreadleVac system and marketed it as Easamatic Brakes.. The TreadleVac is essentially a vacuum booster built onto a special hydraulic section. It does not have a piston in the conventional sense -- that being a rubber cup sealing a cylinder to push fluid ahead of it like a manual master or a modern power brake system. In the TreadleVac the vacuum (or pedal) pushes a fairly large diameter rod into a space that by virtue of a valve that closes as soon as the rod starts to move becomes a sealed fluid filled chamber. The rod does not make any contact with the walls of the chamber but the large mass pushing into the enclosed space full of fluid displaces and forces some of the fluid out to the wheels.