Single Plate Clutch
The new single plate clutch now standard for Model “A”cars and “AA”trucks is composed of two major units, namely, the cover plate assembly A-7563 and the clutch disc assembly A-7550 or AA-7550.
The cover plate assembly consists of a cast iron outer driving plate and a stamped cover plate in which are mounted twelve pressure springs and six release levers. These springs are in direct action against the pressure plate and automatically compensate for all wear of the friction facings. This feature eliminates any necessity of adjusting the release levers.
The driven member or clutch disc assembly is composed of a flat steel disc and two friction facings. The facings are riveted to both sides of the driven disc. The disc is slightly dished in the form of a cone. With this construction the outer and inner edges of the clutch disc facing, start to engage first and as the clutch engages when the pedal is allowed to come back the spring pressure in the clutch flattens out the clutch disc and the entire lining surface picks up the load evenly. This feature assures exceptionally smooth clutch engagement.
Moulded friction facings are used because of their long wearing qualities. They also successfully withstand higher temperatures as they contain no cotton element.
Repair parts and exchanges
The only repair parts dealers will stock are the clutch disc assemblies A and AA-7550, clutch disc facings A-7549B and AA-7549, facing rivets A-22993 and pressure plate and cover assembly A-7563.
Should any part of.the pressure plate and cover assembly fail, return the entire assembly to the Branch, and a new assembly will be furnished at an exchange price of $3.25 net. The price to the customer will be $4.25.
Under no circumstances will dealers attempt to replace any parts in the pressure plate and cover assembly, as the lever height when under spring pressure must be set with specially designed fixtures.
The following is a list of single plate clutch and related parts which will be supplied through service:
((Table pg 296))
The pressure springs automatically compensate for all wear of the friction facings. Readjustment of the release levers must never be made under any circumstances.
The only adjustment for clutch wear is made at the bottom of the clutch pedal. The pedal must have 1 inch free play or movement before it starts to disengage the clutch.
Grease on friction facings will cause the clutch to chatter during engagement or sometimes slip at high speeds. The remedy is to remove the clutch and install a new set of clutch discs facings.
Occasionally, due to an improperly adjusted clutch pedal o r continuous abusive slippage, the clutch pressure plate may develop small radial heat cracks. If the pressure plate is not grooved, and these cracks are not large, simply polish the face and replace the unit. These heat checks will cause no harm.
It is not necessary to return clutch driven members to the factory for replacement of worn friction facings, as this operation may be done in your own shop. Before facings are replaced, make certain that the driven member otherwise is in good condition.
The saw steel driven disc is slightly dished to provide smooth clutch engagement. When new friction facings are installed be certain that the rivets are drawn down tightly.
Drivers should b e instructed that riding the clutch pedal is a bad habit, as it causes the clutch to slip. The foot should be placed upon the clutch pedal for a definite purpose only—that is to change gears.