Engineering manual - SAB 193-233-283 S A-frame (including ATEX)
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008831 en 2022.02
Technical description
4.32 KRACHT oil pump
Fig. 39
The oil pump is an external toothed gear pump, which works according to the positive displace-
ment principle. The pump is equipped with a mechanical seal, cooled and vented through inter-
nally bored channels.
The pump has an integrated by-pass valve – a pressure relief valve with a factory setting of 3.5
bar, see Fig. 40. It is possible to adjust the valve from 0 to 15 bar by removing the hexagon
nut, then setting the response pressure using the adjusting screw and then securing the adjust-
ing screw with the hexagon nut.
Fig. 40
The by-pass valve serves two purposes:
• To protect against overheating by allowing overflow if the oil pressure downstream
pump exceeds the setting of the pressure relief valve. According to KRACHT, the pump
can run continuously with “at least” 50% by-pass without overheating.
• To protect the pump against excessive pressure in case of a blocked discharge line
from the pump. It can also run for a short while with a fully blocked discharge pipe.
Fig. 41
Drive shaft end
Shaft seal
Housing Gear unit
Plain bearing bushes
End cover
External gear pump
+-
Hexagonal nut
- Lower response pressure
+ H
igher response pressure
Adjustment screw
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