North American Clutch & Driveline
Rockford, Illinois
Phone: (800) 383-9204
(815) 282-7960
Fax (815) 282-9160
www.naclutch.com
38
OPERATION
GENERAL INFORMATION
Model SP318AM, SP318SBAM Series Power Take –Offs consist of a manually engaged and
disengaged disconnect clutch mounted on an output in a cast iron housing that is bolted to
the engine. Clutch engagement and disengagement is accomplished by means of an operating
lever on the outside of the PTO housing, which actuates an internal linkage mechanism.
A drive ring is bolted to the engine flywheel. Internal teeth of the drive ring mesh with external
teeth of the clutch driving plate(s). These are the input components of the Power Take-Off, input
components always rotate at engine rpm
Output components of the Power Take-Off consist of a clutch hub that is mounted on the
output shaft, a linkage mechanism for clutch engagement and disengagement and clutch
adjustment components. Clutches designed with multiple clutch driving plates have a clutch
centre plate located between the driving plates. The clutch centre plate and pressure plate
are driven through internal teeth that mesh with external teeth on the clutch hub. Until clutch
engagement is initiated, the output components do not rotate.
During clutch engagement, the clutch pressure plate is moved to clamp the clutch friction
plate(s) against the friction face of the clutch hub (or the centre plate(s). The internal engagement
mechanism of the clutch locks the clutch pressure plate in the engaged position to complete
the drive. Thus, at full clutch engagement while the engine is running, the output shaft is driven
at engine speed.
Grease lubricated main bearings are located in the PTO housing or bearing carrier. Some
designs include a pilot bearing mounted in the engine flywheel to support the front end of the
clutch shaft. However, some designs incorporate a main bearing configuration that does require
use of a plot bearing.
A support plate bolted to the bearing carrier is required to provide sufficient support where
heavy weight and /or side loads exist.