Specifications

Proposal Number PSDF #P09-0004
The brake system shall be a split system. One (1) system serving the rear brakes and one (1) system serving
the front brakes. The two (2) systems shall be connected with a double check valve that shall automatically
shuttle air from the front system to the rear system should loss of air pressure occur. This system shall also
modulate the amount of air so the spring brakes shall apply in direct relationship to the amount of pressure
applied to the treadle valve.
The brake system shall be equipped with a Bendix SR-1 valve to provide modulated spring brakes in the
event there is low air pressure in the rear axle air supply reservoir.
The spring brakes shall be piped in such a manner that if the treadle valve is depressed while the spring
brakes are applied, the spring brakes shall release and remain released as long as the treadle valve is
depressed. They shall reapply immediately when the treadle valve is released.
The piping in the air system shall be 2-ply nylon reinforced color coded tubing for all stationary lines.
AIR DRYER
The air system shall include a MERITOR/WABCO System Saver 1200 air dryer. The dryer shall have a
capacity of 30 CFM of air flow.
The air dryer shall have a spin on desiccant cartridge for ease in servicing the dryer desiccant.
The air dryer shall incorporate an integral turbo cut-off valve. The turbo cut-off valve shall close the path
between the air compressor and the air dryer purge valve during the compressor "unload" cycle. This shall
allow the air dryer to purge the water and contaminates without any loss of turbo boost or engine
horsepower.
A 12 volt, 100 watt heated moisture ejector shall be an integral part of the air dryer. This heater shall be
thermostatically controlled. The electrical connection for the heater shall use a sealed electrical connector to
protect against moisture and corrosion.
AUTOMATIC MOISTURE EJECTORS
All air reservoirs of the chassis air system shall be supplied with automatic moisture ejectors. The reservoir
drain valves shall allow the accumulation of contaminants that are collected in the reservoirs to be drained
off to the atmosphere.
AIR INLET / OUTLET
An outside air system inlet/outlet connection shall be provided and mounted in the driver's cab step area.
This
connection shall be clearly labeled as to the function. A pipe thread frame coupling shall be provided with
1/4" npt threads. The fire department shall install the appropriate hose quick connect fittings.
MERITOR/ROCKWELL/WABCO ABS BRAKE SYSTEM
A four channel, single rear axle model, MERITOR/ROCKWELL/WABCO ABS Braking System shall be
supplied.
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