Mounted pump (without V-belt pulley)

Mechanical water pumps

Basic Information

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What is the function of the water pump? How is a vehicle cooling system constructed? Where is the water pump in the cooling system? What types of water pumps are there? You can find out here.

Task of the Water Pump
Combustion in the engine creates heat. The cooling liquid absorbs the heat from the engine block and cylinder head and releases it into the ambient air through the radiator. The water pump circulates the cooling liquid in the closed cooling system.
Cooling system
1 Radiator
2 Thermostat
3 Water pump
4 Control valve
5 Heat exchanger
6 Cooling jacket
7 Radiator fan
Installation locations and types of drive for water pumps
Depending on their design, mechanical water pumps are located either externally on the engine in their own pump housing or are flanged directly on the engine block. Water pumps that are fitted externally on the engine are driven by a belt that normally also drives additional accessories such as the generator, servo pump or air conditioning compressor. In this case, the force transmission is performed using V-belts or poly-rib belts (poly V-belt, poly- rib).

In passenger cars, flanged water pumps are normally driven via the timing belt of the valve control system. The type of installation makes this water pump type easier to design and fewer components are required compared with water pumps that are fitted externally on the engine. However, the replacement of timing belt driven water pumps is a more labour-intensive process than the replacement of V-beltdriven water pumps. During replacement, the entire timing belt drive of the engine must be opened and disassembled. This is a complex intervention in the control of the camshaft drive. For a great deal of engines, it is essential to have engine-specific professional knowledge.

Special tools and adjustment values such as the valve timing, the belt tension and the start of delivery of the fuel injection pump (where applicable) are required for a large number of engines. Even minor deviations or errors made during this work can cause serious engine damage.
Flanged pump with timing belt drive
Mounted pump (without V-belt pulley)
Design and function of the water pump
Mechanical water pumps are made up of
the following main groups:

1 Drive pulley
2 Bearing with pump shaft
3 Pump housing
4 Sliding ring seal cartridge
5 Impeller
Timing belt driven water pump flanged on the engine
Bearing designs
Mechanical water pumps feature two rows
of ball bearings (Fig. 1) or, in the case of
increased bearing load, combined ball/
roller bearings (Fig. 2). The bearings are
provided with a lifetime grease filling. In
order to prevent the ingress of water and
dirt, the bearings are sealed on both sides
with a radial shaft seal. In water pumps,
the bearing shaft is also a component of
the bearing. This means that the balls or
rollers roll directly off the pump shaft.
Fig. 1: Ball bearing
Fig. 2: Ball/roller bearing

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