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Has anyone heard of this one? Old AACA forum post says,
"My 1934 Buick Model 57 has 4-wheel mechanical brakes with a Vacuum Power Booster.
Properly adjusted, this car will stop as well as any hydraulic system, and will never have a brake fluid leak."
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I have seen vacuum assist for mechanical brakes but dont know what vehicle it came off or was designed for.
Tony
1938 1/2 ton Hope to drive it before I retire
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Mechanical Power Brake Assist: Invented In 1919, RR Was Still Using It Into The Sixties
The development of brakes pretty consistently lagged the development of engines and speed, which made most really old cars very hairy to drive. One of the breakthroughs was the mechanical brake servo, given that the modern vacuum servo was still some time in the offing, as well as hydraulic brakes themselves. How to stop the giant luxury cars of the teens? In 1919, the brilliant Marc Birkigt invented the solution for the superb Hispano Suiza H6, and Rolls Royce quickly licensed the technology. And kept using it well into the 1960s.
This diagram shows the first version of the earlier mechanical system, purely mechanical, where the foot pedal operated both the front and rear brakes, both assisted by the servo. The hand lever operating on the rear brakes is an emergency system. The picture after the jump shows the later version where the servo works on a hydraulic master cylinder.
The servo is very similar to a clutch, and driven off the transmission. Pressing on the brake pedal brings the other face of the servo disc in contact with the driven face, essentially like slipping a clutch. That generates a variable degree of force, which here is transmitted to the master cylinder. In mechanical brake cars, there were linkages running front and back to the brakes (the Hispano Suiza was one of the earlier adopters of four wheel brakes the servo worked on two hydraulic master cylinders. Either way, the mechanical servo system worked quite well, and was reliable. Which probably explains why conservative RR kept it for the new Silver Cloud in 1955.
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Mechanical Power Brake Assist: Invented In 1919, RR Was Still Using It Into The Sixties
The development of brakes pretty consistently lagged the development of engines and speed, which made most really old cars very hairy to drive. One of the breakthroughs was the mechanical brake servo, given that the modern vacuum servo was still some time in the offing, as well as hydraulic brakes themselves. How to stop the giant luxury cars of the teens? In 1919, the brilliant Marc Birkigt invented the solution for the superb Hispano Suiza H6, and Rolls Royce quickly licensed the technology. And kept using it well into the 1960s.
This diagram shows the first version of the earlier mechanical system, purely mechanical, where the foot pedal operated both the front and rear brakes, both assisted by the servo. The hand lever operating on the rear brakes is an emergency system. The picture after the jump shows the later version where the servo works on a hydraulic master cylinder.
The servo is very similar to a clutch, and driven off the transmission. Pressing on the brake pedal brings the other face of the servo disc in contact with the driven face, essentially like slipping a clutch. That generates a variable degree of force, which here is transmitted to the master cylinder. In mechanical brake cars, there were linkages running front and back to the brakes (the Hispano Suiza was one of the earlier adopters of four wheel brakes the servo worked on two hydraulic master cylinders. Either way, the mechanical servo system worked quite well, and was reliable. Which probably explains why conservative RR kept it for the new Silver Cloud in 1955. Now thats a very interesting proposition, is it possible to adapt that technology to a 10935 Chevrolet standard with 4 wheel mechanical brakes? and you mention a diagram, but cant see one in this post? this is the first time that I have never heard about a mechanical servo system, there were some very clever engineers back in the old days. Peter
never give 100% unless you are giving blood.
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When RR was mentioned was a reminder of where I had seen yhe mechanical assist. I have been working on a 47 Bentley of late and it has the mechanical assisted between the pedal and hydraulic master cylinder.
Tony
1938 1/2 ton Hope to drive it before I retire
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Shade Tree Mechanic
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Shade Tree Mechanic
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Another system used by Pierce Arrow I think employed a disc on a quick thread on the driveshaft clamped by a caliper operated by the brake pedal. On application The disc stopped turning and screwed up or down the drive shaft moving the brake operating levers and applying the brakes. Drawbacks included 6" of car travel before the brakes were applied. Be careful while parking!
I suggest it might be difficult to fit to your torque tube
ColinGrant
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A lot of big cars in the '30's had a booster with mechanical brakes....especially GM cars.
Gene Schneider
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