BENDIX SD-06-1800 User Manual

Bendix® SL-3™ & SL-4™ Stop Light Switch

MACHINE

SCREWS

SD-06-1800

TERMINAL

SCREWS

COVER

TERMINAL

CONNECTOR

CONTACTS

PLUNGER

BODY

FIGURE 1 - BENDIX® SL-3™ STOP LIGHT SWITCH

DIAPHRAGM

SPRING

WASHER

DESCRIPTION

The stop light switch is an electro-pneumatic switch and operates in conjunction with the brake valve and stop lights by completing the electrical circuit when a brake application is made.

CONTACT

PISTON

O-RING

DIAPHRAGM

FIGURE 2 - BENDIX

TERMINAL

SCREWS

SL-4™ STOP LIGHT SWITCH

10 VENT PLUG

COVER

SPRING

CONTACT

STRIP 15

GASKET

BODY

PREVENTIVE MAINTENANCE

Important: Review the Bendix Warranty Policy before

performing any intrusive maintenance procedures. A warranty may be voided if intrusive maintenance is performed during the warranty period.

OPERATION

When a brake application is made, air pressure from the brake valve enters the cavity below the diaphragm. At approximately 5 psi, the air pressure underneath the diaphragm overcomes the force of the spring and moves the piston or plunger until the contact points close, completing the stop light electrical circuit and lighting the stop lights.

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, the Bendix

SL-3™ and SL-4™ switches should be inspected every 6 months or 1500 operating hours, whichever comes first, for proper operation and electrical connections. Should the SL-3™ or SL-4™ switch not meet the elements of the operational tests noted in this document, further investigation and service of the valve may be required.

TESTING FOR SERVICEABILITY

CLEANING AND INSPECTION

OPERATING TEST

1. Apply the brake valve and note that the stop light lights before the delivery pressure reaches 7 psi.

2. Release the brake valve and note that the stop light goes “off”.

LEAKAGE TEST

1. With the brakes fully applied, no leakage is permitted at the stop light switch. If the stop light switch does not function as described or if leakage is excessive, it is recommended that it be replaced with a new unit

or repaired with genuine Bendix

brand replacement

parts available at authorized Bendix parts outlets.

REMOVING

1. Disconnect the electrical connections at the stop light switch.

2. Disconnect the air line to the stop light switch.

3. Remove the stop light switch.

INSTALLING

1. Install in a convenient location for servicing.

2. Install with the pipe tap pointing to the ground and keep it high for adequate drainage.

3. Connect the stop light switch in series in the stop light circuit.

4. Keep the stop light switch terminals away from frame members to avoid grounding.

5. Connect the pipe tap to the brake chamber supply line so that the stop light switch will operate whether the foot or hand valve is applied.

DISASSEMBLY

BENDIX® SL-3™ SWITCH

1. Place hex portion of body in a vise.

2. Using a large end wrench on cover ﬂ ats, turn cover (1) in a counterclockwise direction and remove from body .

3. Remove terminal nuts, terminal screws (2) and terminal connector (7) from cover.

4. Remove spring (3), plunger (4), washer (5) and diaphragm (6) from body.

BENDIX® SL-4™ SWITCH

1. Remove two machine screws (7) and remove cover (8).

2. Remove the terminal nuts and terminals (9) from cover .

3. Remove the vent plug (10) from cover.

4. Remove spring (11), contact strip (12), piston (13) and o-ring diaphragm (14) from body.

Clean all metal parts in cleaning solvent. Wipe rubber parts dry with a cloth.

Inspect contact points for pits or wear. If pitting is not too severe, the points may be reconditioned by ﬁ ling with a distributor point ﬁ le. If points cannot be reconditioned, they

™

should be replaced. The contact strip in the SL-4

switch

may be turned over to use the other side of the contacts. Check the spring for signs of deterioration; Replace if

discolored. The spring in the SL-3™ switch carries the current of the electrical circuit involved; consequently, in the case of excessive current, as might be caused by a short, the spring will be overheated and ruined.

Inspect cover and body. If cracked or damaged, replace. Only genuine Bendix service parts should be used for

replacement.

ASSEMBLY

SL-3™ SWITCH (Figure 1)

1. Insert terminal screws (2) in the cover (1), making sure the terminal connector (7) is properly positioned.

2. Secure terminal screws with washers and nuts, or terminal clips, as the case may be.

3. Place diaphragm (6) in the body.

4. Position the contact plunger (4) on diaphragm.

5. Position spring (3) on the plunger.

6. Place washer (5) on the diaphragm and screw the cover (1) into the body . T orque to 30 foot pounds. Make certain the vent hole in the cover is open.

SL-4™ SWITCH (Figure 2)

1. Position terminal screws (9) in the cover (8) and secure with washers and nuts or terminal clips. Place the vent plug (10) in cover.

2. Place o-ring diaphragm (14) and piston (13) in the body . The o-ring diaphragm should be installed with its ﬂ at side adjacent to the piston.

3. Place the gasket (15) in place on the body and contact strip (12) on the piston (13).

4. Position cover assembly on the gasket and secure with machine screws. Torque to 20 inch pounds.

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