Where the crankshaft extends through the crankcase, a leakproof seal must be maintained to prevent the refrigerant and oil from escaping and also to prevent air from entering the crankcase when the pressure in the crankcase is lower than the surrounding atmospheric pressure. This is accomplished by crankshaft seal assemblies. There are several types of seals including the rotary seal, and the diaphragm. The rotary seal shown in figure 6-2 consists of a stationary cover plate and gasket, a rotating assembly which includes a carbon ring, a neoprene seal, a compression spring, and compression washers. The sealing points are located (1) between the crankshaft and the rotating carbon rings, and sealed by a neoprene ring; (2) between the rotating carbon ring and the cover plate, and sealed by lapped surfaces; and (3) between the cover plate and the crankcase, and sealed by a metallic gasket. The seal is adjusted by adding or removing metal washers between the crankshaft shoulder and the shaft seal compression spring.

A stationary bellows seal is illustrated in figure 6-3. It consists of a bellows clamped to the compressor housing at one end to form a seal against a rotating shaft seal collar on the other. The sealing points are located (1) between the crankcase and the bellows, and sealed by the cover plate gasket; (2) between the crankshaft and the shaft seal collar, and sealed by a neoprene gasket; and (3) between the surface of the bellows nose and the surface of the seal collar, and sealed by lapped surfaces. The stationary bellows seal is factory set for proper tension and should not be altered.

The rotating bellows seals, figure 6-4, consists of a bellows clamped to the crankshaft at one end to form a seal against a stationary, removable

Figure 6-2.Rotary seal.

Figure 6-3.Stationary bellows seal.

shaft seal shoulder on the other end. The sealing points are located (1) between the crankshaft and bellows, and sealed by a shaft seal clamping nut; (2) between the removable shaft seal shoulder and the crankcase and sealed by a neoprene gasket; and (3) between the bellows nose piece and the shaft seal collar, and sealed by lapped surfaces. This type seal is also factory set.

Figure 6-4.Rotating bellows seal.

Figure 6-5.Diaphragm type seal.

The diaphragm seal, figure 6-5, consists of a diaphragm clamped to the crankcase at its outer circumference and to a fulcrum ring at its center. The fulcrum ring forms a seal collar which is locked to the diaphragm. The sealing points are located (1) between the outer circumference of the diaphragm and the crankcase, and sealed by a copper ring gasket; (2) between the fulcrum ring and the diaphragmsealed at the factory and not to be broken; (3) between the fulcrum ring and the rotating shaft seal collar, and sealed by lapped surfaces; and (4) between the shaft seal collar and the crankshaft shoulder, also sealed by lapped surfaces.

The tension in a diaphragm seal is adjusted by adding or removing diaphragm-to-crankcase gaskets to obtain the specified deflection. For information on handling, cleaning, and replacement of shaft seal assemblies, consult the

Figure 6-6.Unloader mechanism in unloaded position.

manufacturers technical manual or the directions enclosed with every new seal.