TM-9-2350-256-20-1

TM 9-2350-256-20-1

0007 00

UNIT MAINTENANCE

RECOVERY VEHICLE, FULL TRACKED: MEDIUM, M88A1

COOLING SYSTEM

THEORY OF OPERATION

Cooling System

Air Cooling

Air for cooling enters the engine compartment through the grille doors. The top of the engine is shrouded and encloses two

gear-driven, axial-flow cooling fans (1) which draw the air through the cylinder fins and oil coolers and discharge the hot air

vertically from the shroud. Sheet metal baffles and deflectors direct the flow of cooling air across the cylinders.

The cooling fans (1) are attached to hubs and are mounted on shafts which are driven by the engine-driven fan drive clutch

assembly.

The fan drive shaft and gear shift are driven by a horizontal drive shaft.

The fan clutch is oil cooled. The fan clutch drive and driven disks are loaded by the centrifugal action of clutch balls and springs

housed in the clutch assembly. The balls and springs are in the driven member and apply upward force to the clutch disks. The

clutch oil enters the fan drive vertical shaft from the fan drive housing through an annular groove in the shaft. The depth of the

groove controls the amount of oil flow. The oil flows through a central hole in the shaft to a distributor where it is dispersed to

the two ball bearings and the clutch disks. The oil moves between the clutch disks by centrifugal action and drains back through

the fan drive housing into the engine oil pan. The fan clutch is designed to slip under deep water fording conditions where the

resistance of the water exceeds the friction of the clutch.

Figure 1.

Cooling System.

Oil Cooling

Two engine oil coolers (2) and two transmission oil coolers (3) are mounted on the sides of the engine above the cylinders. The

cooling fans (1) draw air through the oil cooler cores to cool the oil being circulated within the coolers.

END OF WORK PACKAGE

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