CUP-TAPERED 9W5165 - Caterpillar

The safe and reliable operation of all motor vehicles depends on proper service and repair procedures. The procedures recommended and described in this manual are effective methods for performing service operations.This manual contains information which should be followed to minimize the risk of personal injury to service personnel or damage to vehicles through unsafe service procedures.This information does not cover all the possible service hazards. Accordingly, anyone using a service procedure or tool not recommended must first be satisfied that their safety or the vehicle's safety will not be jeopardized by the method selected.
General Description
The EL-740 Air Compressor is two cylinder, air or water cooled, and engine lubricated. It can be base or flange mounted.The air compressor has a rated capacity of 7.4 CFM which is the displacement in cubic feet per minute (CFM) at 1250 rpm.The EL-740 Air Compressor is designed with a ball-bearing at the front (the shaft end of the air compressor) and a sleeve-type rear bearing. Several models carry ball bearings front and rear. The air compressor is designed with a one-piece crankshaft.Pistons are made of aluminum alloy. Each piston has three compression rings: one in the top groove, and two in the second groove (some older style air compressors have only two compression rings; one in each groove). In the groove below the wrist pin (the oil rail groove) is one expander ring and two oil rails. Thrust buttons are used on both ends of the wrist pin to retain the pin in the piston rod.Rod bearings are replaceable insert type.All valve components are installed within the head. The exhaust valves use a screw-in, spring-loaded, disc-type assembly located in the bottom of the head. The inlet valve guard and valve are pressed into the inlet cavity in the bottom of the head.The unloader mechanism components are housed in the unloader assembly which is bolted to the top of the head. The unloader pins extend from the unloader assembly, through the cylinder head to the inlet valve cavity where they hold the inlet valves open when the air system is at maximum pressure.Air Compressor Operation
During the down stroke of each piston, air is drawn into the cylinder bore through the inlet valve in the cylinder head. As each piston begins its upstroke, the inlet valve closes and the air above the piston is compressed.When the pressure in the cylinder block becomes greater than the air pressure in the cylinder head above the exhaust valve, the exhaust valve is forced off the valve seat. Air passes through the exhaust port into the head cavity and into the air line leading to the air reservoir.As the piston starts a down stroke, the exhaust valve returns to its seat. Compressed air is prevented from returning to the cylinder block, and the inlet and compression cycle is repeated.Governor Operation
The governor, operating in conjunction with the air compressor unloader mechanism, automatically controls air pressure in the air system between the predetermined maximum and minimum pressures.The air compressor runs continually