Wichita Clutch LKM Clutch - Manual (Page 6)

45 I N D U S T R I A L C L U T C H P R O D U C T S
Model LKM
LKM Marine Clutch Application Information
The selection chart on the previous page is suitable for
forward/reverse main propulsion service at 125 PSI
actuation.
For controllable pitch propellers, dredge pumps, winches,
and fire pumps use the following service factors.
Example: Centrifugal dredge pump Disconnect clutch
application.
IIn np pu utt P Pa arra am me ette errs s
The engine is rated 3000 HP and the shaft the clutch is to
be mounted on is rotating at 900 RPM. The available air
pressure is 150 PSIG.
The Model LKM-225-B (rated at 510,000 LB-IN) is selected
from the static torque column shown in the operational data
chart on the previous page. This unit is the nearest size that
meets or exceeds the value of 437,674 LB-IN required.
The allowable speed for the Model LKM-225-B is 1200 RPM
and exceeds the operating speed of 900 RPM. The selection
is appropriate from a torque and speed standpoint.
Dredge pumps can draw extraneous matter into the pump
which may suddenly stall the pump impeller. This places a
huge shock on the drive system and the clutch is called
upon to act as a fuse in these instances. A review of the
magnitude of the actual applied service factor is always
required to be certain the drive system components can
withstand these overloads. It may be necessary to reduce
the clutch service factor which increases the likelihood of
clutch damage but saves a more costly drive system repair.
The preferred way to reduce the service factor is to adjust
the operating air pressure accordingly and maintain the
clutch size as originally selected.
The following procedure may be used to calculate the air
pressure required for any desired service factor. In this
example, the recommended service factor was 2.5. We
selected a Model LKM-225-B clutch since it was the closest
unit that met or exceeded the calculated torque requirement
of 437,674 LB-IN. Note that the actual service factor is 2.91.
If, by way of example, it was decided that a service factor
of 2.0 was required, the supply air pressure should be set at
103 PSI.
To summarize, a Model LKM-225-B operating at 103 PSIG
will provide a 2.0 service factor for this application.
Tact = Actual Static Capacity = Cat. Stat. Rating x
Supply Press
Rated Press
Tact = 510000 x = 612000 LBIN
150
125
Actual Serv. Fact. = = = 2.91
Tact
Working Torq
612000
210083
Operating Pressure =
125 x Reqd. Serv. Fact. x Work Torq
Cat. Stat. Torq. Rating
Operating Pressure = = 103 PSIG
125 x 2.0 x 210083
510000
Working Torque = = = 210083 LBIN
HP x 63025
RPM
Minimum Static Torque = Work Torque x Service Factor
= 210083 x 2.5 = 525208 LBIN
3000 x 63025
900
Minimum Catalogue Rating = Static Torque Reqd x
Rated Press
Supply Press
Minimum Catalogue Rating = 525208 x = 437674 LBIN
125
150
Service
Machinery Factor
Main Propulsion 1.8
Cont. Pitch Prop.
Winches, Centrifugal 1.65
Fire Pumps
Centrifugal Dredge Pumps 2.5
Main Propulsion Continuous Consult
Slip from Engine Idle Factory