Hidromax

Hydro-Max™ Hydraulic Brake Booster and Master Cylinder

Technical Manual

BOSCH

Important Service Notes
The information in this publication was current at the time of printing. The information presented in this publication is subject to change without notice or liability. The information contained in this publication is intended for use by properly trained and equipped professionaltechnicians. It is NOT for the "Do It Yourselfer". Failure to follow safety and repair procedures can result in personal injury, or damage to vehicles, components and equipment.

Correspondence concerning this manual should be addressed to: Robert Bosch Corporation ATTN: Hydraulic Actuation & Truck Brake Engineering 401 North Bendix Drive South Bend, Indiana 46628 Fax: 574-237-2210August  2003

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Table of Contents
1 General Description.............................................................................................................................

Hydro-MaxTM Booster................................................................................................ 1Master Cylinder.........................................................................................................1

Principle of Operation........................................................................................................................ 3 Hydro-MaxTM Booster................................................................................................ 3Master Cylinder.........................................................................................................5 Electrical Operating System......................................................................................7 Basic Operation of Booster and Master Cylinder......................................................8
9 Electronic Monitor Module........................................................................................Application Information...................................................................................................................... 13 Hydraulic Fluids........................................................................................................13 Brake Fluid Tubing, Hoses and Fittings....................................................................13Booster Fluid Tubing, Hoses and Fittings.................................................................14
15 Booster Fluid Source..................................................................................................

Installation Recommendations...................................................................................16Pedal Return Springs.................................................................................................17 Pedal Stop and Proper Spring Load..........................................................................18

Trouble Shooting..................................................................................................................................19

Printed in the United States of America © 2002 Robert Bosch Corp.All rights reserved.

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General Description
  The Hydro-MaxTM is a hydraulically powered brake booster which provides power assist for applying hydraulic brakes.  A booster combined with a master cylinder (refer to Figure 1) forms the hydraulic brake actuation unit.  A typical assembly is shown in Figure 1.  The booster reduces thepedal effort required to apply the brakes as compared to a non-power system.

BRAKE FLUID RESERVOIR

FLOW SWITCH INLET PORT OUTLET PORT PEDAL ROD

MOUNTING FLANGE

MASTER CYLINDER HYDRO-MAXTM BOOSTER
SECONDARY OUTLET PORT DIFFERENTIAL PRESSURE SWITCH FLUID LEVEL INDICATOR SWITCH PRIMARY OUTLET PORT RELAY BACKUP PUMP

Figure 1 Hydro-MaxTM

Booster and Master Cylinder Assembly

Hydro-MaxTM Booster...