Re: Bendix Treadle Vac, Myths, Fiction and Facts

Posted by PackardV8 On 2017/2/26 10:59:45

Briefly:
There was no such thing as a power brake system PRIOR to the BTV. (now watch some chucklehead cite an obscure exception that only lasted maybe 2 years during the 1930's on some very low production car).

So somewtime about 1951 or 1952 there was sudden "demand" for power brakes.

BUT, the eng'ring departments had to come up with a way REAL FAST to shoe horn a power brake system onto cars that were simply left over designs from the 1940's. A 1940's design that was never designed to accomodate a power brake (keep in mind damned near every car built prior to 1955 had treadle type clutch and brake pedals, UNDER FLOOR mounted master cylinders, INLINE engines (not many LARGE V type engines etc etc).

SO the BTV with it's SMALL BUT LONG STROKE piston was an "11-th hour" attempt to overcome any WIDE SWEEPING major design changes. SUCH AS brake pedal redisign, major changes to allow frame clearences or relocateing other components of the car to accomodate ANY power brake unit that is at least 3 times the size of ANY standard brake unit.

The Compensator vlave was necessary to allow for the LONG STORKE SMALL BORE BTV master cylinder. And it is the COMPENSATOR VALVEE that renders the BTV a HIGH MAINTENANCE SHORT SERVICE LIFE master cylinder!!!!!

Note that the compensator valve is peculiar to ONLY the BTV master cylinder.

WHICH MEANS: That ANY master cylinder made by ANY mfg'er at ANY time or ANYWHERE in the world does NOT have a compensator valve.

Bottom line:
The BTV was a very early attempt to cobble up a power brake system at the last minute onto a "platform" automotive design left over from the late 1930's.

Thats why BTV only lasted about 10 years. Once the horse power revolution of 1955 gained steam thru the late 50's then the aautomotive platform or design of the cars became WIDER, and lower silhouette and designed for more modern automotive needs such a power steering, brakes, BIG WIDE V8's, dual exhausts, HIGHER ROAD SPEEDS etc etc.

Get the picture???