The automobile owner's guide

by Frank B. Scholl

BORG AND BECK CLUTCH

The new Borg and Beck Clutch is provided with a thrust bearing at the inner end of the clutch sleeve, which does away with the friction between the parts, and eliminates the need of a clutch brake.

The clutch is mounted in the customary way in a housing which contains both the flywheel and the clutch.

Fig. 107. Borg and Beck Clutch

Referring to the sectional view, [Fig. 107], the action of the clutch is clear if it is kept in mind that among the rotatable parts only the driven group, comprising of the disk A and the shaft B, can stand still when the flywheel is running. All the other rotatable parts are anchored to the flywheel, and must revolve and drive with the latter. The clutch brake was formerly mounted at the inner end of the clutch shaft, and has been replaced by the thrust bearing shown at C.

When the clutch is disengaged there is no friction between the shaft B, and the throw out sleeve D. The thrust bearing takes the rotating drag of the clutch shaft, thereby eliminating the necessity for a brake to check the spinning action. The friction and power action is readily understood as, when the clutch is thrown in, all the rotating parts are friction locked into a single combination and revolve as one with the flywheel.

The power of the release clutch spring E, acting through the throwout-collar F, and the bell crank pivot G, drives the thrust shoes outwardly with a lever wedge toggle combination of powers against the overhanging, inward beveled face to the thrust ring H, since the parts on which they are mounted are backed against the cover wall or rigid end of the clutch casing. It therefore follows that the full part shafting effect of the thrust is communicated to the thrust ring H, and the latter, in being driven hard toward the flywheel, sets up between itself and the inner casing wall a friction grip sufficiently powerful to stop the slippage of the asbestos rings upon the polished faces of the discs, thus giving the drive to the car.

When the pedal is depressed to release the clutch, the retracing parts telescope the coil of the spring E, until it occupies nearly a single plane. The withdrawing parts also release the clutch shoes a sufficient distance from the face of the thrust ring H to permit the latter, together with its companion friction ring, to back away from the disc, thus breaking the friction grip and permitting it to come to a stop, while the flywheel and the parts of the clutch anchored to it are left free to revolve idly.

The release disc A is so light that its spinning does not continue except for a very short time and does not offer any clashing action on the gears. The full thrust of the spring transmitted through the powerful lever toggle action to the friction grip parts is always sufficient to lock the driving flywheel parts, and the driven disc, into a fixed nonslipping relation for a full driving action; but it is still always within control of the driver, through the foot lever, to let the clutch into engagement by degrees, and thus by a gradual increase of the friction grip, gradually overcome the starting slippage.

Adjustments.—Taking up adjustments are provided by means of bolts acting through adjustment slots in the cover. When the bolts are loosened and shifted in their cover slots, they control and shift with them an adjustment ring which brings all the shoes to new seats against the nonslipping thrust ring and these seats being farther up the inclines of the tapered ring, the ring is necessarily thrust much farther toward the other friction parts, thus compensating the wear.

The adjustment for throw-out can be controlled by taking up the friction grip adjustment, the latter being identical with the take up adjustment just described, as these too are taken care of by the same mechanical means to make the adjustment on the clutch.

Disc Clutch Cleaning; Dry Plate.—Dry plate clutches do not require any oil, except that the grease cups (which provide lubrication for the sleeve shaft and bearings) be filled weekly and given a half turn every second day. The housing and plates should be cleaned whenever slipping becomes noticeable. To do this remove the cover from the housing, and the drain plug from the bottom, hold the clutch out, and squirt kerosene over the plates with a dope gun. This will remove the grease from the plates, and also any dirt or grit that may have lodged in the bottom of the housing.

Disc Clutch Cleaning; Wet Plate.—The wet plate clutch is cleaned in the same manner as the dry plate, except that the plug is first removed from the bottom of the housing and the oil drained off before using the kerosene. After the plates and housing have been cleaned, replace the drain plug and fill the housing up to the clutch shaft with a heavy cylinder oil.