DESCRIPTION
The low oil pressure shutdown plunger, Fig. 13-I, is part of the low oil pressure shutdown device, which is contained in the governor. Although it is a protective device it is not an accessory to the engine. Refer to Section 12 for description and maintenance of the low oil pressure shutdown device

DESCRIPTION
The combination differential water and crankcase pressure detector, Fig. 13-2, is a mechanically operated, pressure-sensitive device used to determine abnormal conditions of the engine cooling system and crankcase pressures. If potentially harmful conditions exist, this protective device will cause engine shutdown. The water pressure portion of the detector balances the differential pressure of the water pump output and the water pump input against the air box pressure to hold an oil relief valve in the latched position. When the differential pressure across the water pump becomes less than the air box pressure, Fig. 13-3, the diaphragm moves causing the oil drain valve to open and dump engine oil from the low oil sensing device in the governor. The governor senses low oil pressure and initiates low oil shutdown. Bleed holes are provided between the pump inlet and outlet diaphragms and the pump inlet and air box diaphragms to visually indicate a leak. This device provides protection against water pump cavitation, which can result from low coolant level, excessive coolant temperature, exhaust gases in the cooling system, or several other cooling system failures. The water portion of the detector will trip whenever the cooling system is drained.

The crankcase pressure portion of the device consists of an oil relief valve, comparable to the one in the water portion, held in a latched position until a positive pressure is built up in the crankcase. The oil relief valve is released and lube oil pressure to the engine governor is relieved, Fig. 13-4. As in the water portion, the governor senses low oil pressure and initiates engine shutdown

WARNING: Following an engine shutdown because the engine pressure detector has been actuated, do NOT open any handhole or top deck covers to make an inspection until the engine has been stopped and allowed to cool off for at least two hours. Do NOT attempt to restart the engine until the cause of the trip has been deter-mined and corrected. The action of the pressure detector indicates the possibility of a condition within the engine, such as an overheated bearing, that may ignite the hot oil vapors with an explosive force, if air is allowed to enter. If crankcase pres-sure detector can not be reset, do NOT operate the engine until the detector has been replaced, since the diaphragm backup plates may be damaged

DESCRIPTION
An overspeed mechanism is provided as a safety feature to stop the injection of fuel into the cylinders should the engine speed become excessive.
Fig. 13-6 shows the mechanical ovespeed trip mechanism. If the engine speed should increase to the specified limits, the overspeed mechanism will shut down the engine.
A trip shaft extending the length of each engine bank under the camshaft is provided with a cam at each cylinder, which when rotated, contacts a spring-loaded catch pawl mounted on each cylinder head, and located directly under the injector rocker arm. In the overspeed trip housing on the front of the engine, the trip shafts are connected to springoperated links and a lever mechanism. A reset lever on the trip lock shaft, when pulled towards the right bank, puts tension on an engaging a notch in the trip lock lever shaft. This is the normal running position, in which the cams on the trip shaft are held away from the rocker arm catch pawls.
The overspeed trip release mechanism is incorporated in the right bank front camshaft counterweight. It consists of a flyweight held by an adjustable tension spring. When engine speed exceeds the set limit, the tension of the spring is overcome by the centrifugal force acting on the flyweight, causing the flyweight to move outward to contact the trip pawl. This allows the actuating spring, acting through connecting links, to rotate the trip shafts. Consequently, the trip shaft cams contact and raise the injector rocker arm pawls preventing full effective injector rocker arm roller contact on its cam. This prevents fuel injection and stops the engine.
Upon resetting, by counterclockwise movement of the reset lever, Fig. 13-7, the trip shaft cams release the injector rocker arm catches. Rotation of the camshafts on starting the engine lift the rocker arms slightly allowing the catch pawls to resume unlatched position, releasing the injector rocker arm for normal operation

To adjust the overspeed trip, shut engine down, remove the cover from right side of overspeed trip housing and turn adjusting nut, Fig. 13-9, to increase or decrease spring tension as required. To increase engine speed at which overspeed trip operates, increase spring tension.
After the adjusting nut has been moved, the locknut must be tightened and the engine run to test speed at which trip operates. The speed rise of the engine from idle to trip should be made in 20 to 30 seconds. Several adjustments may be required before final setting of tripping speed is reached.

The hot oil shutdown device, Fig. 13-10, consists of a thermostatic valve and the associated piping.
Fig. 13-10 -Hot Oil Shutdown Installation
The valve is located in the discharge elbow of the main lube oil pump. Piping from the valve is connected into the oil pressure line between the differential water and crankcase pressure detector and the governor. There is also drain line piping from the valve to the governor drive housing.
When oil temperature rises to 124°-126° C (255°260° F), the thermostatic valve will open and the pressure oil is allowed to pass through the valve and drain into the governor drive housing. The governor
senses the resultant low oil pressure, and initiates an engine shutdown