1
Bendix
®
SL-5
™
Stop Light Switch & Bendix
®
DS-2
™
Combined
Stop Light Switch & Double Check Valve
SD-06-1804
DESCRIPTION
The Bendix
®
SL-5
™
stop light switch is an electro-pneumatic
5 psi non-grounded switch that operates in conjunction with
the brake valve and stop lights by completing the electrical
circuit and lighting the stop lights when a brake application
is made.
The DS-2
™
combined stop light switch and double check
valve, as the name implies, combines a SL-5
™
stop light
switch with a DC-4
™
double check valve to perform the
function of both. It operates in conjunction with the brake
valve and hand control valve by directing the flow of air from
whichever delivers the higher pressure into a common delivery
line and to the stop light switch, closing the electrical circuit
to the stop lamps.
The stop light switch can be used with either 12 or 24 volt
systems.
The stoplight switch is not a serviceable item; and if found
defective in either device, the complete unit must be replaced.
The shuttle valve in the DS-2
™
valve is serviceable and may
be replaced.
Both the SL-5
™
switch and the DS-2
™
valve have been tested
and meet the requirements of FMVSS 121.
OPERATION
The stop switch mechanism is identical in the SL-5
™
switch
and the DS-2
™
valve.
When a brake application is made, air pressure from the
brake valve enters the cavity below the diaphragm. The air
pressure below the diaphragm moves the piston until it
contacts the leaf spring. The leaf spring travels past a fulcrum
at which point the leaf springs snaps a shorting bar which
mates with the contact strips. The stop light electrical circuit
DS-2
™
VALVE
SL-5
™
STOP
LIGHT
SWITCH
FIGURE 1 - DS-2
™
COMBINED STOP LIGHT SWITCH & DOUBLE CHECK VALVE SECTIONAL
RIVET
INLET PORT
INLET
PORT
CONTACT
STRIP
FULCRUM
SHORTING
BAR
TERMINAL
OUTLET PORT
LEAF
SPRING
PISTON
DIAPHRAGM
SHUTTLE
VALVE
(CHECK
VALVE)
