Axial-type fan, five-bladed, creates an additional air flow through the core of the cooling system radiator

It is fixed on the hub 15 of the driven shaft of the fluid coupling and placed in the casing

When the fan rotates, the shroud generates airflow through the heatsink core to improve cooling efficiency.

Kamaz Fluid Coupling

The fan drive is hydraulic, it consists of a hydraulic clutch and a switch for its operation.

The fan drive fluid coupling provides torque transmission from the engine crankshaft to the fan and reduces dynamic loads that occur when the crankshaft speed changes abruptly.

The switch automatically turns the fan on or off.

The fluid coupling is installed in the front of the engine coaxially with the crankshaft in the cavity formed by the front cover 1 of the block and the bearing housing 2.

The drive shaft assembly with the casing 3, the drive wheel 10, the pulley shaft 12 and the generator pulley 11, connected by bolts and rotating in ball bearings 8, 19, constitute the leading part of the fluid coupling. It is driven by the engine crankshaft through splined shaft 6.

Driven wheel 9 assembled with shaft 16 and fan hub 15 fixed on it, rotating in ball bearings 4, 13, constitute the driven part of the fluid coupling.

The fluid coupling is sealed with rubber cuffs 17, 20. On the inner toroidal surfaces of the driving and driven wheels, there are radial blades cast together with the wheels. There are 33 of them on the driving wheel, 32 on the driven wheel.

The interblade space of the wheels forms the working cavity of the fluid coupling.

The transmission of torque from the driving wheel 10 of the fluid coupling to the driven wheel 9 occurs when the working cavity is filled with oil.

When the engine is running, the oil coming from the pressure section of the oil pump through the switch channel falls on the blades of the rotating drive wheel, is carried away by it, while acquiring kinetic energy.

Internal oil circulation is established in the cavity of the wheels (shown by arrows).

Oil particles, hitting the blades of the driven wheel, give it energy, ensuring the rotation of the driven parts and the fan.

The speed of the driven wheel depends on the amount of oil entering the fluid coupling cavity.

A sharp change in the engine crankshaft speed is accompanied by slippage of the fluid coupling drive wheel relative to the driven wheel, which reduces dynamic loads in the drive.

Fluid clutch switch

The switch (Fig. 2.), which controls the operation of the fan drive fluid coupling, is installed in the front of the engine on the nozzle so that its thermal force sensor 7 is in the fluid flow supplied from the pump to the right row of cylinders.

The switch has three fixed positions that determine the fan operation mode.

Positions (A, R, O) of the fan drive fluid clutch switch

Auto mode - lever set to A.

In the event of an increase in the temperature of the coolant washing the thermal force sensor, the active mass in its cylinder begins to melt and, increasing in volume, moves the sensor rod and ball 9.

At a liquid temperature of 85...90°C, ball 9 opens the oil channel in housing 5.

Oil from the main line of the engine through the channels in the circuit breaker housing, block and its front cover, tube 5 (see Fig. 3) and channels in the drive shaft enters the working cavity of the fluid coupling; in this case, the torque from the crankshaft is transmitted to the fan impeller.

When the coolant temperature is below 85°C, the ball, under the action of a return spring, closes the oil channel in the housing and the oil supply to the fluid coupling stops. At the same time, the oil in the hydraulic coupling is drained through the hole in the casing 3 into the crankcase of the engine and the fan is turned off.

The fan is off — the lever is set to position O (Fig. 3), Oil is not supplied to the fluid coupling.

The impeller can rotate at a low frequency under the action of frictional forces that occur during rotation in the bearings and cuffs of the fluid coupling.

The fan is always on - the lever is set to P.

The hydraulic clutch is constantly supplied with oil, regardless of the temperature of the coolant, the fan rotates constantly at a frequency approximately equal to the crankshaft speed.

Main rehydraulic clutch operation - automatic.

If the hydraulic clutch switch fails in automatic mode (characterized by engine overheating), it should be switched on to a permanent mode (set the switch lever to position A) and, as soon as possible, eliminate the malfunction of the switch