These instructions pertain to the single disk style ball lock clutch as found on most 1955 and newer DB tractors with 1/2" V-belts, although the later styles with the 5/8" belts are very much the same. This clutch featured a single asbestos facing riveted to the drive pulley, and a pressure plate machined into the outer reverse drive pulley (clutch sheave), which is threaded onto an adjustment sleeve in the hub. The reverse drive pulley was included on this clutch even if reverse was not an option on the subject tractor. These instructions have been paraphrased from an actual David Bradley owner's manual.

CLUTCH ADJUSTMENT

This clutch is a rolling ball lock clutch, and it is necessary to push the handle forward until the clutch snaps into the engaged position. Although this clutch is very durable, adjustment may be necessary at some point. This is accomplished by removing the Allen set screw from the clutch sheave, and turning the clutch sheave clockwise exactly 30 degrees. Replace the Allen set screw in the second threaded (formerly empty) hole in the clutch sheave. Only one set screw is used, leaving one open hole in the sheave. The set screw must line up with a flat on the threaded hub to avoid damaging threads. The two hole arrangement allows adjustment in smaller increments. Do not put set screws in both holes! To do so would cause thread damage due to one or the other not lining up with a flat on the hub.

If the clutch sheave is difficult to turn on the adjusting sleeve, two nails (pins, bolts, etc.) may be inserted in the holes provided in the adjusting sleeve and two screwdrivers (prybars, etc.) may be used to turn the clutch on the sheave as shown in figure AA. Many collectors make up a tool for the hub with pins or bolts in the end of a piece of flat steel bar, spaced to match the holes in the hub.

If the facing becomes glazed or covered with grease or oil, it may need to be cleaned. Wash the facing with gasoline or kerosene and wipe dry. Brake cleaner is a more modern alternative which also works well. Just be careful of the paint. A glazed surface can be broken up with a wire brush.

REPLACEMENT AND REPAIR

FACING

1) Disengage clutch

2) Loosen Allen set screw (16) in clutch sheave (7) and unscrew sheave from adjusting sleeve.

3) Remove groove pin (17) and adjusting sleeve (18).

4) Remove all burrs from groove pin and shaft.

5) Remove pulley (4) with facing (5) by sliding it from the shaft. Watch for falling balls! There are 10 (sometimes 11) steel balls inside the collar on the opposite side of the clutch pulley, behind the pressure washer (10). If you are careful (and lucky) the pressure washer (10) might keep them in place around the shaft when the pulley is removed. However, it is possible that vibration or other factors might cause the washer to slip a bit and the balls may spill on the floor. If that happens, be sure to catch them.

6) Remove all rivets (6) from clutch facing (5) and pulley.

7) Thoroughly clean all parts of grease and oil.

8) Rivet new facing (5) to pulley (4).

9) Reverse above procedure to reassemble, being sure that all balls are in their proper position. See step 8 below for more instructions on installing the balls.

10) If other parts are replaced besides the clutch facing, be sure that each part slips freely over the input shaft of the transmission. These parts must slide freely.

PULLEY BEARING

In the event the bronze bearing (15) in the clutch pulley (4) should need to be replaced, the manual instructs as follows:
Align new bearing against the old one. Drive out old bearing using a soft wood block.
However, if you have access to, or can make a bearing driver, use the driver in conjunction with an arbor press (if available) or use a hammer with caution.

THRUST COLLAR

1) Remove pulleys as outlined above.

2) Remove Cotter from control rod and handle, and remove rod from clutch yoke lever (1).

3) Remove cotter (2) and rivet (3) from clutch yoke (1) and transmission.

4) Slip clutch yoke lever (1) and pressure ring (11) from input shaft, being careful to catch all (10 or 11) of the balls from the pressure ring (11).

5) Remove clutch pressure washer (10).

6) Pry Thrust collar (8) from input shaft. Use equal pressure from both sides if possible.

7) Replace (new) thrust collar (8) by sliding over input shaft and tapping carefully, using a piece of pipe or tube for a driver.

8) Reverse above procedure to reassemble. After the clutch pressure ring (11) has been slipped over the input shaft, slip clutch pressure washer(10) over shaft. Cup index finger around underside of input shaft between presure ring (11) and pressure washer (10) and drop 10 (or 11) steel balls in cup made by finger, then slip pressure washer (10) and steel balls inside pressure ring (11) being sure all of the balls remain inside the pressure ring. This operation is a bit tricky, and many collectors resort to simply turning the transmission on its side so the balls don't spill on the floor. Complete reassembly can now be made, reversing above procedures.

This style of ball lock clutch was used on the following models:

With 1/2" drive belt: 57583, 57597, 57598, 57599, 575100, 575102, 575104, 575105, 575111, 575119, 575120, 575131, and 575134.

With 5/8" drive belt: 575112, 575121, 575135, 575138, 575139, 575142, 575143, and 575144.