Servicing the Bendix Hydrovac


Series 1 hydrovac

Hydrovac is the trade name for a B-K “one-unit” vacuum power braking system for use on trucks, tractors or buses equipped with hydraulically actuated brakes. It combines into one compact assembly a hydraulically actuated control valve, a tandem-piston power cylinder and a hydraulic cylinder. The assembly is a complete self contained vacuum power brake “system” which eliminates the need for external levers or link age. Connections to the vehicle braking system are entirely hydraulic, consisting of a line from the vehicle brake system master cylinder to the Hydrovac, and a hydraulic line from the Hydrovac connecting to the wheel cylinders of the vehicle brake system. Contrasted with conventional vacuum power brake systems, the Hydrovac is connected hydrauLically instead of mechanically, both to the vehicle master cylinder and to the wheel cylinders.
Among the advantages which make Hydrovac an important development in vacuum power braking are:

• Simplified installations.
• External levers and links eliminated.
• Unlimited latitude for location of the Hydrovac.
• Combined physical actuation with power braking as in other B-K systems.
• Unimpaired physical actuation in event the power system fails due to accidental damage or other cause.

*One waggieltly remarked that. with a long enough hose, the hydrovac could be “held Ga the drive lap” and sti1l work!

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