2
Air System
Check Valves
Check valves are used in many locations throughout the air system. There are several types of check
valves; the photographs shown here do not necessarily look exactly like the units installed in your bus.
Single Check Valve
Single check valves are used to permit the flow of air in one direction only and prevent air flow in the re
-
verse direction. Figure 6-21, Figure 6-22, Figure 6-23, and Figure 6-
24
show typical single check valves.
An arrow indicating the direction of air flow is cast into the body of each valve.
operation
Air flow in the normal direction moves the check ball or disc from
its seat, and the flow is unobstructed. Flow in the reverse direction
is prevented by the seating of the ball or disc, which is caused by a
drop in upstream air pressure and assisted by the spring.
preventive maintenance
Every 50,000 miles, 6 months, or 1,800 operating hours, disassem
-
ble, clean, and inspect all parts.
operation and leakage check
It may be easiest to simply remove the check valve from the vehicle
for testing. To test, apply air pressure to the outlet side of the check
valve. Coat the open end of the valve with soap suds. A 1" bubble in
5 seconds is permissible.
Figure 6-21, SC-3
Single Check Valve
Figure 6-22, Ball Type
Single Check Valve
Figure 6-23, Disc Type (inte-
gral seat) Single Check Valve
Figure 6-24, Disc Type (replace-
able seat) Single Check Valve
Summary of Contents for LOW FLOOR
Page 18: ...Specifications 18...
Page 58: ...Preventive Maintenance 58...
Page 110: ...Engine 110...
Page 138: ...Transmission Driveline Rear Axle 138...
Page 182: ...Suspension 182...
Page 260: ...Air System 260...
Page 420: ...Electrical System 420 Deutsch DT Series Connectors...
Page 421: ...Electrical System 421...
Page 422: ...Electrical System 422 Deutsch HD 10 Series Connectors...
Page 423: ...Electrical System 423...
Page 424: ...Electrical System 424 Deutsch HD 30 Series Connectors...
Page 425: ...Electrical System 425...
Page 442: ...Heating Air Conditioning 442...
Page 492: ...Body and Interior 492 Figure 11 33 USSC Seat Assembly...
Page 493: ...Body and Interior 493 Figure 11 34 USSC Seat Suspension Assembly...
Page 495: ...Body and Interior 495 Figure 11 37 Seat Air Connections...