Fig. 1 Treadle Type Brake Valve

Fig. 3 Brake Valve Applied - Normal Operation

TM-5-3820-256-24-4 Drilling System Well Rotary Truck Mounted Air Transportable 600 Feet Capacity Model LP-12 NSN 3820-01-246-4276 Manual
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SERVICE MANUAL BENDIX TYPE E6 & E7 DESCRIPTION Two types of Bendix brake valves are used; they are treadle type (E6) and suspended type (E7). The brake valve is the control unit of the air brake system. It provides the operator of the vehicle a means of applying or releasing the vehicle brakes. The brake valve can either be treadle operated or fitted with a suspended pedal lever. Both the treadle and suspended brake valves are equipped with two separate supply and delivery circuits for service and emergency braking, providing the driver with a graduated control for applying and releasing the vehicle brakes. The primary circuit is that portion of the valve between the spring seat which contacts the plunger and the relay piston. The secondary circuit is that portion between the relay piston and exhaust cavity. Fig. 1 Treadle Type Brake Valve 1 Primary Delivery 2 Secondary Delivery The primary circuit is similar in operation to a standard single circuit air brake valve and under normal operating conditions the secondary circuit portion is similar in operation to the relay valve. Both the primary and secondary circuits of the brake valve use a common exhaust check valve, OPERATION The text and illustrations contained herein actually pertain to the treadle type brake valve. The treadle and suspended type valves differ in that the suspended pedal valve is turned over and the valve body is equipped with an exhaust port at a 90 degree angle at the top to exhaust air out the side of the cab. Applying Normal Operation - Primary Circuit Portion of Brake Valve (Fig. 3) When the brake pedal is depressed, the plunger exerts force on the spring seat, rubber graduating spring and primary piston. The primary piston which contains the exhaust valve seat, closes the primary exhaust valve. As the exhaust valve closes, the primary inlet valve is moved off its seat allowing primary air pressure to flow out the primary delivery port. Fig. 2 Suspended Type Brake Valve 3 Secondary Supply 4 Primary Supply CTS-4079 CHAPTER IV PRINTED IN UNITED STATES OF AMERICA Page 3

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