THEORY OF OPERATION
The 924G Wheel Loader consists of the following functional systems: engine, powertrain, brake, electrical, steering,
hydraulic, ride control, and earthmoving equipment.
This work package explains how the systems and components of the machine work together. A functional description is
provided for each major component and system.
The 924G has a sound suppressing ROPS/FOPS cab with insulation, heater, and air conditioning, which allows for all-
weather operation. The ROPS/FOPS must be removed for transport by C-130 and C-141 aircraft, highway, and GIC rail.
General. The loader is equipped with a Caterpillar 3056E DIT ATAAC diesel engine with six inline cylinders, generat-
a. Diesel fuel is drawn from the tank by an electric fuel transfer pump, filtered by a primary fuel filter and a fuel/water
separator, routed to the fuel injection pump and secondary filter, and then injected through the fuel injector nozzles
into the engine cylinders.
b. Air is drawn in through dry-type, replaceable filter elements. A precleaner removes incoming dust from the air.
c. An electronic control module (ECM) functions as the governor and computer for the fuel system.
Cooling System. The cooling system provides coolant to the engine. Coolant is circulated through the engine by a gear-
driven water pump. Hydraulic oil, transmission oil, and aftercoolers are located near the radiator. The engine oil cooler
is mounted on the right side of the engine.
Lubrication System. The engine lubrication system consists of a gear-driven oil pump, oil filter, oil cooler, and oil pan.
The engine is lubricated by cooled and pressurized oil that is circulated through the engine block and head.
a. The exhaust system routes exhaust gases from the engine through the exhaust manifold and turbocharger. The gases
flow into exhaust pipes and a muffler to the atmosphere above the cab.
b. The turbocharger has a wastegate, which helps improve engine emissions.
a. The loader is equipped with an ECM-controlled Caterpillar autoshift transmission with four forward speeds and three
b. Manual, automatic, or economy modes of transmission operation can be selected.
c. To increase operator efficiency, direction of travel can be controlled by using either a steering column-mounted shift
lever or a transmission direction control switch (F/N/R switch) on the loader control joystick.
d. A transmission neutralizer system allows the operator to disengage the transmission by pressing the service brake
pedals. This serves to stop the machine while increasing hydraulic response. This function can be turned off using the
transmission neutralizer override switch, or it can be adjusted by the operator.
Front Axle. This axle is fixed and is mounted to the frame.
Rear Axle. This axle is trunnion mounted to allow axle oscillation of ±8 degrees.