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CLARK speed Powershift Transmission 5-8-16000

 With the engine running, the converter charging pump draws oil from the transmission sump and directs it through oil filters to the regulating valve located on top of the transmission . From the regulating valve it is then directed through the control cover on the transmission to the converter and to the transmission clutches.  

The pressure regulating valve mounted on the top of the transmission remains closed until required pressure is delivered to the transmission for actuating the direction and speed clutches. This regulator valve consist of a hardened valve spool operating in a closely fitted bore. The valve spool is backed up by a spring to hold the valve spool against its seat until the oil pressure builds up to the specified pressure. The valve spool then moves toward the spring until a port is exposed along the side of the bore. The oil can flow through this port into a distributor which directs the oil into the converter inlet port.


After entering the converter, the oil is directed through the stator support to the converter cavity and exits between the turbine shaft and converter support. The oil then passes through an oil distributor which directs the oil out of the converter by way of a down stream regulator valve and then to the oil cooler. After leaving the cooler the oil is directed through a hose to the lubricating oil inlet on the transmission, then through a series of tubes to the transmission, bearings, and clutches. The oil then returns to the transmission sump.

A safety valve is built in the transmission control cover and will open to bypass oil only if an excessive is built up to a blocked passage.

The rear compartment of the converter unit also houses the converter output shaft. A flexible hose provides an overflow to the transmission sump.

The three members of the torque converter are composed of a series of blades. The blades are curved  in such a manner as to force the oil to circulate from the impeller to the turbine, through the reaction member again into the impeller. This circulation causes the turbine to turn in the same direction as the impeller. Oil enters the inner side of the impeller and exits from the outer side of the turbine. It then exits from the inner side of the turbine and after passing through the reaction member, again enters the inner side of the impeller.

Converter "Stall" is achieved whenever the turbine and impeller shaft are stationary and the engine is operating at full power or wide open throttle 

CAUTION: do not maintain "Stall' for more than 30 seconds at a time. Excessive heat will be generated and may cause converter or transmission seal damage.

In converter equipped with lock-up clutches, a hydraulic clutch, similar to the transmission clutches is used to "lock" the engine mechanically to the output shaft. This is accomplished by hydraulic pressure actuating the lock-up clutch which in turn locks the impeller cover to the turbine hub. During lock-up the converter turns at 1 to 1 speed ratio.

the down stream regulator valve on the converter consist of a valve body and regulator spool. The spool is backed up by a spring to hold the valve until converter oil pressure builds up to specified pressure. The valve is used to maintain a given converter pressure to insure proper performance under all conditions.

The direction or speed clutch assembly consist of drum with integral gear teeth and bore to receive a hydraulically actuated piston. A piston is inserted into the bore of the drum. The piston is "Oil tight" by the use of sealing rings. A friction disc with teeth is inserted into the drum and rests against the piston . Next a disc with splines at the outer diameter is inserted. Discs are alternated until the required total is achieved. After inserting the last disc, a series of springs and pins are assembled in such a manner that these springs rest on teeth of the piston.

A heavy back-up plate is then inserted and secured by a snap ring. A hub with I.D with O.D splines is inserted into the splines of discs with teeth on the inner diameter and splined shaft extending through the clutch support. This hub is retained by a snap ring. The discs and inner shaft are free to increase in speed or rotate in the opposite direction as long as no pressure is present in the direction or speed clutch.

To engage the clutch, the shift lever is placed in the desired position. This allows oil under pressure to flow from the control cover valve, through a tube in the transmission case, to a chosen clutch. Once into the drum, oil is directed through a drilled hole into the rear side of the position bore. Pressure of the oil forces the piston and disc over against the heavy back-up plate. The discs, with teeth on the outer diameter, clamping against discs with teeth on inner diameter, enables the clutch drum and drive shaft to be locked together and allows them to turn as a unit.


There are bleed balls in the clutch drums which allow quick escape for oil when the pressure to the piston is released .

The transmission gear train consist of six shafts (1) input shaft, (2) Reverse shaft, (3) Idler shaft, (4) First and Third shaft, (5) Second and fourth shaft, (6) Output shaft.

A screen mounted in a frame is positioned on the bottom of the transmission case, to screen out any foreign material. This screen is covered by the sump pan. This pan is provided with magnets to  catch any metallic particles.ave an axle declutching units as optional equipment, this unit consist of a split output shaft with a sliding splined sleeve to engage or disengage the axel. This is acc

Some transmission may homplished by manually shifting a lever in the operator's compartment which is mechanically connected to the shift fork on the clutching unit sliding sleeve. This unit, of course is only used on the four-wheel drive machine. On the front drive only or the rear wheel drive only, the output shaft is a one-piece type and an output flange assembled only on the required end. offers diagnostic & repair information beyond the printed manual for over 32,000 vehicles.

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