BEARING 8N7928 - Caterpillar

Important! Please Read
When working on or around air brake systems and components, the following precautions should be observed:1. Always block vehicle wheels. Stop engine when working under a vehicle. Depleting vehicle air system pressure may cause vehicle to roll. Keep hands away from chamber push rods and slack adjusters; they may apply as system pressure drops.2. Never connect or disconnect a hose or line containing air pressure. It may whip as air escapes. Never remove a component or pipe plug unless you are certain all system pressure has been depleted.3. Never exceed recommended air pressure and always wear safety glasses when working with air pressure. Never look into air jets or direct them at anyone.4. Never attempt to disassemble a component until you have read and understand recommended procedures. Some components contain powerful springs and injury can result if not properly disassembled. Use only proper tools and observe all precautions pertaining to use of those tools.Description And Operation
General
The function of the air compressor is to provide and maintain air under pressure to operate devices in the air brake and/or auxiliary air systems.Description
The Tu-Flo 501 is a two cylinder, single stage, reciprocating compressor with a rated displacement of 12 cubic feet of air per minute at 1250 R.P.M.The Tu-Flo 501 is constructed from two major assemblies, the head and the crankcase. The head houses the discharge valving and is installed on the upper portion of the crankcase. The crankcase is a one piece casting combining the cylinder block and the crankcase. The upper portion of the casting houses the cylinder bores and inlet valving; and the lower portion, the crankshaft and main bearings. Various mounting and drive configurations, required by the numerous vehicle engine designs, are obtained by bolting different mounting flanges, end covers, and base adapters to the crankcase. Two horizontal governor mounting pads are located on either side of the upper portion of the crankcase to provide convenient governor mounting.Two methods are employed for cooling the Tu-Flo 501 during operation. The cylinder head is connected to the engine's cooling system, while the cylinder bore portion of the crankcase has external fins for efficient air cooling. All Tu-Flo 501 compressors utilize the engine's pressurized oil system to lubricate the internal moving parts.A nameplate is attached to the crankcase to identify the compressor. The nameplate displays a Bendix piece number or in some cases an engine or vehicle manufacturer's piece number, along with a serial number. Operation
General
The compressor is driven by the vehicle engine and is operating continuously while the engine is running. Actual compression of air is controlled by the compressor unloading mechanism and the governor. The governor is generally mounted on the compressor and maintains the brake system air pressure to a preset maximum and minimum pressure level.Intake and Compression of Air (Loaded)
During the down stroke of the piston, a slight vacuum is created between the top of the piston and the head, causing the flat circular inlet valve to move up and off its seat. (Note