2202L5JE-DA-C5-N_2015.05.
5 Maintenance and Inspection
Compound 2-stage Screw Compressor
5.4 Disassembly and Inspection
1612LSC Speed Increaser Type
5-29
Balance Piston and Balance Piston Sleeve
5.4.9 Balance Piston Cover
Disassemble the balance piston cover when pulling out the rotors or inspecting the side bearing [28-2]
or balance piston [30].
a) Loosen all hexagon socket head cap screws [24] 3 or 4 rotations, lightly tap the side of the balance
piston cover [22] with a soft hammer, and peel off the sticking balance piston cover gasket [23].
b) In this state, drain the oil from the balance piston and the side bearing block inside the suction
cover. When the oil has been drained, remove all screws apart from the one on the upper side.
While holding down the balance piston cover, remove the remaining screw and remove the balance
piston cover.
5.4.10 Balance
Piston
When the screw compressor is operated, the
thrust load on the M rotor is large and the
rotation compared to the F rotor is fast.
Therefore, the life of a thrust bearing on the M
rotor would normally be much shorter than the
life of a thrust bearing on the F rotor. To reduce
the thrust bearing load on the M rotor, a
hydraulic piston is installed at the end of the
high-stage M rotor shaft in order to cancel the
thrust load.
* A balance piston is not required on the
low-stage because, due to low-pressure
conditions, the difference in life is not as big
as the high-stage.
5.4.10.1 Disassembly
Change in Shape of the 1612**C Suction Cover [5-2]
* It might be a too old episode.
Due to the modification in shape design of the high-stage suction cover [5-2] in February 1975, the
attachment of a balance piston sleeve [33] became necessary. Accordingly, the balance piston [30] and
the balance piston cover [22] were newly created.
a) Using external snap (retaining) ring pliers, remove the snap ring [32] that secures the balance
piston [30] to the rotor shaft (following picture to the left). Screw in two M8 eyebolts to remove the
balance piston (following picture to the right). It is not necessary to remove the balance piston key
[31] embedded in the rotor shaft.
