BENDIX SD-03-4520 User Manual

Bendix® SDS-9600™ Trailer Suspension Dump Valve

SD-03-4520

1/4" NPT

RESERVOIR

PORT

EXHAUST PORT

SHOWN WITH

OPTIONAL SILENCER

FIGURE 1 - BENDIX® SDS-9600™ TRAILER SUSPENSION DUMP VALVE PORT IDENTIFICATION

DESCRIPTION

The SDS-9600™ trailer suspension dump valve is utilized
on spread axle trailers, to negotiate tight turns at low
speeds by limiting torsion forces on the rear trailer axle.
These forces can damage tires, frames, and suspension
components.

When activated, the SDS-9600
valve exhausts (dumps) a portion of the air out of the rear
trailer axle suspension taking the weight off of that axle,
and transferring it to the forward trailer axle. The trailer
can then pivot on the forward trailer axle in a turn.

Maintaining a portion of the air in the rear axle reduces
damage to the air suspension, saves on suspension and
system air, reduces time needed to re-infl ate the system
when required, and reduces tire chattering, all of which may
occur if all of the air is exhausted from the suspension. The
SDS-9600™ trailer suspension dump valve then returns air
to the rear axle suspension upon driver input (deactivated)

™

trailer suspension dump

3/8" NPT

DELIVERY PORT

1/4" NPT

CONTROL

PORT

EXHAUST PORT

SHOWN WITH

DIAPHRAGM

®

The Bendix

SDS-9600™ trailer suspension dump valve
is a pilot operated normally open three-way valve with
a high-capacity exhaust, inversion control, and delivery
pressure hold feature. The function of the valve is to apply
delivery pressure to the rear axle of a spread axle trailer
suspension, and then to exhaust the delivery pressure
through a high-capacity exhaust upon the input of a control
signal. Upon exhaust, an internal mechanism of the trailer
suspension dump valve stops the exhausting of air and
holds the delivery pressure at a minimal pressure.

Porting is as follows:

• (2) 3/8 inch NPT delivery ports

• (1) 1/4 inch NPT control port

• (1) 1/4 inch NPT supply port

• (1) 1/4 inch NPT reservoir

• (1) Exhaust port with Diaphragm
or optional 3/8 inch NPT port

or when vehicle speed is in excess of 10 mph.

1/4" NPT

SUPPLY PORT

3/8" NPT

DELIVERY PORT

1

FRAME RAIL

SPREAD AXLE TRAILER

2" MINIMUM

CLEARANCE

2" MINIMUM

FRAME RAIL

90° MAXIMUM

FIGURE 2 - MOUNTING THE SDS-9600™ TRAILER SUSPENSION DUMP VALVE

OPERATION

CLEARANCE

EXHAUST

the SDS-9600™ valve should be inspected every 6 months
or 1500 operating hours, whichever comes fi rst, for proper

MOUNTING ORIENTATION

The SDS-9600™ trailer suspension dump valve is mounted
to the trailer frame rail or cross-member. It is preferred that
the valve be mounted on the backside of a cross-member

operation. Should it not meet the elements of the operational
tests noted in this document, further investigation and
replacement of the valve may be required.

REMOVAL

with the exhaust port facing down. Mounting on the top side
of a cross-member is acceptable, providing the exhaust port
is facing rearward on the vehicle. Never mount the valve
with the exhaust port facing upwards. The valve should
have at least 2 inches of clearance between the exhaust
port and any other surface. Refer to Figure 2.

PREVENTIVE MAINTENANCE

Secure the vehicle with spring brakes or blocks. Drain the
reservoir which supplies the SDS-9600
disconnect the connecting air lines. Remove the screws
that secure the valve to the trailer frame rail. Remove the
valve.

INSTALLATION

Typical system schematics for the SDS-9600™ valve are

Important: The SDS-9600™ trailer suspension dump

shown in Figures 3 and 4.

valve is not serviceable, but must be inspected for proper
operation as a part of routine vehicle maintenance.

Inspect the mounting hardware and replace if necessary.
Check connecting air lines for integrity and foreign

No two vehicles operate under identical conditions, as
a result, maintenance intervals may vary. Experience is
a valuable guide in determining the best maintenance
interval for air brake system components. At a minimum,

material, replace if necessary. Re-connect the air lines.
Check the operation of the valve by charging the system
and performing the service check as described in this
manual.

2"

™

valve. Mark and

3/8"-16 X .50

MOUNTING

HOLES (2)

2