1
®
RESERVOIRS
SD-04-400
TYPICAL SINGLE COMPARTMENT RESERVOIR
DESCRIPTION
The reservoir is a storage tank; its function is to provide a
volume of compressed air for braking which will be adequate
in relation to the volume used by the brake chambers and
auxiliary devices. Reservoirs also provide a location in the
system where the air, heated by compression, may be cooled
and the water vapor condensed.
Bendix
®
reservoirs are built in accordance with SAE Standard
Air Brake Reservoir Test Code and Inspection Procedure
SAE J-10-a. They are made from steel sheet, with stamped
heads and rolled shells. The seams are electrically welded,
and each reservoir is internally coated for corrosion resistance.
Each reservoir is tested at 300 PSI hydrostatic pressure.
Reservoirs are supplied in various pipe ferrule arrangements
and lengths and in diameters from 3-1/2" to 14" having
various volumes from approximately 100 cubic inches to
7600 cubic inches for tractors and trailers. All ferrules are
tapped to SAE dryseal pipe thread standards.
Reservoirs are also supplied in double and triple compartment
configurations and in some cases include an integral check
valve between compartments in a double compartment
reservoir. Figure 1 illustrates a two compartment reservoir.
Two styles of check valves are shown in Figures 2 and 3.
Figure 3 is the current design.
OPERATION
The reservoirs in an air brake system primarily serve to store
energy in the form of compressed air. They also perform the
less obvious function of providing a means of cooling the air
as delivered from the compressor and thereby condensing
water vapor into a liquid as well as collecting oil passed by
the compressor. This water and oil collects as an emulsion;
the greatest amount in the reservoir nearest the compressor.
It should be drained off either manually or by means of an
automatic drain device.
OPERATION OF INTEGRAL CHECK VALVE
The integral check valve provides a one-way passage of
air from the upstream compartment to the downstream.
This check valve may serve to meet the legal requirement
for a check valve to protect the service brake system in
case of failure in the compressor, discharge lines or first
reservoir compartment.
PREVENTIVE MAINTENANCE
All reservoirs should be drained daily. If an automatic drain
device is used, it should be checked periodically for proper
functioning. If an air dryer or aftercooler is used, the
reservoirs should be manually drained periodically to verify
the proper function of the drying device. Reservoirs, which
have collected a considerable oily emulsion, should be
drained by opening a drain cock and allow to drain until all
drainage stops.
MAINTENANCE OF THE INTEGRAL CHECK
VALVE
Every six months, 1,800 operating hours or 50,000 miles
the check valve on the two compartment reservoir should
be tested for leakage, as outlined below, and parts inspected
for damage or deterioration and replaced if considered
unserviceable.
OPERATING AND LEAKAGE TEST FOR TWO
COMPARTMENT RESERVOIR CHECK VALVE
1. Determine the direction of the air flow.
2. Build up system air pressure to governor cut-out and
turn off engine.
3. Completely drain compartment #1 (see Figure 1).
NOTE: It may be necessary to remove automatic drain
device if so equipped.
4. To determine pressure retention in #2 compartment,
perform one of the following tests:
a. Check dash gauge (if connected to #2 compartment).
b. Apply service brake (if supplied from #2
compartment).
