The double-line bypass valve (Fig. 1) is designed to control one actuator (spring energy accumulator) through one of two independent circuits of choice
It consists of a body 1 with a cover 3, a seal 2 and two seats in them.
The output I of the valve is connected to the accelerator valve line, the output II - to the line of spring energy accumulators, the output III - to the line of the emergency brake release valve.
When the car is released by a manual brake valve (Fig. 1. b), compressed air from the parking brake reservoir is supplied through the accelerating valve to terminal I, pressing the seal 2 to the cover seat 3, and then through terminal II enters the cylinders of spring energy accumulators.
When the car is released by the emergency release valve (Fig. 1. c), compressed air is supplied to terminal III and seal 2 is pressed against the seat in housing 1.
The vehicle is braked by releasing compressed air from the spring energy accumulators, while the seal 2 remains pressed against the seat and the air passes freely through port II to port I or III.
When compressed air is simultaneously supplied to terminals I and III, seal 2 can take up a neutral position.
Repair of a two-way bypass valve
We unscrew the screws 6 (fig. 3) with washers 5 fastening the cover 4 to the body 1
Disconnect the cover and the valve body, take out the ring 3 and the seal 2
We wash the valve parts in diesel fuel, blow it with compressed air and check the technical condition
We install the ring and seal 2 in the cover 4 and body 1
Insert screws 6 with washers 5 into the holes of the cover and body and screw them in
We test the valve for performance and tightness
We connect the device 6 according to the scheme shown in Figure 4
Open and close tap 1 fine control several times
Using fine control valve 1, we set pressure on pressure gauges 2 and 3 to 19.6 kPa (0.2 kgf / cm 2 ), while air leakage is allowed from device 6 (3 cm 3 /min) from the free end of the pipeline 5.
At pressure above 39.3 kPa (0.4 kgf/cm 2), air leakage is not allowed
When the air is quickly released from the receiver 4 (5 l) to a pressure of 19.6 kPa (0.2 kgf / cm 2), the device 6 must be completely sealed.
At pressure below 19.6 kPa (0.2 kgf/cm 2), air may leak from the free end of pipeline 5
Connect device 6 according to the diagram, swapping pins 1 and 2, repeat the test.