88
Air System
KNEELING SySTEM OPERATION
The front suspension kneeling system allows the driver, when the bus is stopped, to override the air sus-
pension height control system and kneel (or lower) the front air suspension. Kneeling the bus reduces the
front step height and reduces the wheelchair ramp angle. Reducing the step height or ramp angle makes
access into the bus easier for handicapped passengers. The kneeling system allows lowering the front
suspension and holding it at the lowered height in any position from normal ride height to fully lowered.
To raise the bus back to normal ride height quickly, the kneeling system includes a fast fill feature. This
will raise the front suspension back from fully lowered to normal ride height in 2-5 seconds. If required
to facilitate the wheel chair ramp deployment, the kneeling system can also be used to over raise the
front suspension to provide a front suspension height above the normal ride height.
The KNEEL switch on the dash or driver’s console is a three position, self centering toggle switch.
When the driver holds the switch in the KNEEL position, the kneeling system will block the air flow
from the suspension height control valve and exhaust the air in the front suspension air bags. The kneel-
ing system will continue to exhaust the air pressure as long as the KNEEL switch is held in the KNEEL
position. When the driver stops holding the toggle switch in the KNEEL position, the switch is spring
loaded to return to the center (OFF) position. When the switch returns to the center position, the kneel-
ing system will stop exhausting air from the air bags, but the hold function will remain engaged to pre-
vent the air bags from re filling with air. This holds the bus in the kneeled or lowered position.
To return the bus to normal ride height, momentarily toggle the KNEEL switch to the RAISE position
(you do not need to hold the switch in that position). This turns on a timer which engages the fast fill
feature for 3-4 seconds. This fast fill feature delivers air directly from the accessory air tank to the front
suspension air bags, quickly raising the bus. After 3 seconds the fast fill feature is automatically turned
off as the bus nears normal ride height, and the hold feature is automatically turned off as well. This al-
lows the suspension height control valve to function. The suspension height control valve will make the
final height adjustment.
The over-raise feature is utilized by holding the KNEEL switch in the RAISE position. As long as the
KNEEL switch is held in the raise position, the fast fill feature will remain on, providing air directly
from the accessory air tank, and will keep the hold feature engaged, preventing the suspension height
control feature from trying to reduce the ride height back down the normal ride height. The over-raise
feature can only be used when the bus is stopped.
The Low Floor front suspension kneeling system consists of a kneeling valve module which contains
three air solenoid valves in the single module:
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...
