SD-02-4600 ® Bendix® DD-3™ & SD-3™ Safety Actuators SERVICE DIAPHRAGM SEPARATOR AUXILIARY DIAPHRAGM PUSH PLATE & SHAFT LOCKING ASSY.
DESCRIPTION The DD-3™ and SD-3™ are air operated actuators with a mechanical push shaft lock. The DD-3™ actuator (see Fig. 1) is a double diaphragm device which provides braking for service, emergency, and parking. It is available in two sizes: type 24 and type 30. The SD-3™ actuator is a single diaphragm device used primarily on off-highway vehicles. It provides service braking and parking. It is available as a diaphragm type in type 30 (see Fig.
RELEASING (SD-3™ ACTUATOR) To release the park application, air pressure in excess of 40 psi must be applied at the lock port and a service application slightly greater than the locked-in application made. For practical purposes, a full reservoir application should be made and held for 5 seconds to produce sufficient forward motion of the shaft to allow disengagement of the lock mechanism. Various control systems are used to achieve the proper sequence of control signals.
5. Spread clamping rings slightly, just enough to slip rings off plates, It may be necessary to use a soft mallet to break the clamping rings loose. If clamping rings are to be reused, caution should be taken so they are not distorted. 6. Remove auxiliary pressure plate, auxiliary diaphragm, service pressure plate, service diaphragm (with separator, if present). On SD-3™ actuators, pressure plate and service diaphragm only. 7. Place non-pressure plate assembly on a smooth surface with the push plate down.
16. (SD-3™ Actuator) Install diaphragm, pressure plate, and clamping ring. 17. (DD-3™ Actuator) The DD-3™ actuators are supplied with two different diaphragm constructions. Figure 1 shows one construction with a metal separator between the service and auxiliary diaphragms. The separator snaps over a bead on the service diaphragm. The service diaphragm piece number for this assembly is 246371 for the type 30 and 246365 for the type 24.
WARNING! PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH: 5. When working on or around a vehicle, the following general precautions should be observed at all times. 1. Park the vehicle on a level surface, apply the parking brakes, and always block the wheels. Always wear safety glasses. 2. Stop the engine and remove ignition key when working under or around the vehicle. When working in the engine compartment, the engine should be shut off and the ignition key should be removed.
