AUTOMOTIVE TROUBLE SHOOTING
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Year Published: 1942
Format: 16mm
Description: This black and white, declassified US Army training film, created in 1942 and released in 1943, (TF 10-980, full title: Automotive Trouble Shooting Part 11c, Section 2, Chevrolet 4x4 and G.M.C. 6x6 Steering System Adjustments) offers troubleshooting advice for mechanics calibrating the steering of military automobiles (TRT: 15:24). Title cards: "This Film is Restricted" over a stenciled banner "Restricted" and "Official Training Film, War Department" with a US War Office seal (0:08). "Produced by the Signal Corps for the Commanding General Services of Supply." Titles continue over shots of mechanics hands, wrenches at work (0:22). A mechanic works with jack lifts under the chassis of a Chevrolet G506 1 ½ ton 4x4 truck (produced as the Chevy G7100, and originally G4100 models). He zeroes in on the steering column. He inserts a bar in a wheel. A closeup shows even weight distribution. The other wheel demonstrates excessive play, indicating loose pinion bearings (0:45). The tie rod is disconnected by removing the clamp bolt and yolk. The upper bearing cap follows in closeup. Shims are handled with care (1:46). Shims are removed from the lower bearing cap from a reverse angle, as heavy grease drips out (2:45). Proper steering knuckle resistance is demonstrated, then the tie rod is reconnected (3:11). The toe of the wheels is checked, using a telescopic toeing gauge. A helper drives forward slowly (3:50). The gauge reads 1/16". The steering arm clamp bolt nut is locked (4:25). The mechanic climbs behind the steering wheel and turns it gently, testing. The separate components of the steering gear assembly. The steering shaft worm gear and tapered bearings in closeup. A ball nut is added in a cross-section shot, then filled with ball bearings and tubular guides. A nut locks the assembly housing together (5:16). Closeup on the mesh of two gears teeth. Calibration is adjusted with a screw and nut (8:11). The mechanic at the wheel loosens a bracket underneath the dashboard, then climbs out of the truck (8:35). The steering rod is disconnected from the pitman shaft (9:04). A lock nut is loosened and a screw is turned. Then, the worm gear bearings are adjusted (9:29). Passenger’s side POV: The Mechanic returns and rotates the steering wheel smoothly back and forth, finding the center (10:46). Re-tightening the steering gear assembly with a wrench. The steering wheel is re-tested to ensure an increased load and consistent resistance (12:12). A highlighted section of a mechanic’s manual: "Using J-544 Steering Gear Checking Scale, measure the pull at the rim of the wheel…" An illustration indicates the proper positioning of a checking scale (13:00). Checking alignment of the steering column jacket. The mechanic re-aligns the steering column jacket, working from the driver’s side wheel well (13:25). The steering column is fixed in place, and the drag link is re-connected (14:09). The mechanic checks the wheel one last time, ensuring a job well done (14:51). "The End" (15:03). The "G506" truck chassis depicted in this film was manufactured in mass quantity by the Chevrolet Motor Division of GM during the World War II era. This model of vehicle became the standard truck for the US Army and Air Corps during the 1940s, as over 150,000 such vehicles were purchased. Of these, roughly 47,700 were shipped to the Soviet Union under the "Lend-Lease" program.
Complete Record:
Transcription
[Music] [Music] it has been reported that this vehicle leads to the right when running such a condition when definitely attributed to the steering system usually indicates that the steering knuckle assemblies are loose on their pivots to determine whether a steering knuckle is loose a bar is inserted in the wheel to release its weight and the wheel is rocked there is no up and down movement of this knuckle it is satisfactory the other steering knuckle is checked in the same manner excessive play is found here indicating that loose trunnion bearings cause the vehicle to lead to the right the bearings will be adjusted after the wheel has been removed the tie rod is disconnected by removing the clamp bolt and the tie rod yoke then the upper and lower bearing caps are removed the trunnion bearing adjustment is made by adding or removing shims of an equal thickness at the upper and lower bearing caps care is exercised in removing the shims to prevent misalignment of the steering knuckle assembly when the caps are reinstalled this equal thickness of shims is removed from the top and bottom bearing caps in order to keep the front axle universal joint properly centered in the housing proper centering keeps wear on the joint at a minimum when the steering knuckle support is free of end play a 2000 shim is removed from beneath each bearing cap to pre-load the bearings with the pivot bearings properly adjusted a slight resistance should be encountered when the steering knuckle assembly is moved as is shown here then the tie rod is reconnected whenever the trunnion bearings are adjusted the toe in of the wheel should be checked and reset if necessary when the telescopic towing gauge is used it is placed between the wheels with the ends of the gauge resting on the bulge of the tires the gauge is set at zero the height of the gauge on each wheel is adjusted so that the chains at either end of the gauge just touch the floor the vehicle is then moved forward until the gauge is the same distance from the floor as it was at the front of the wheels then the gauge reading is noted on this vehicle it is 1 16 of an inch which indicates the correct amount of towing since the towing is found correct the steering arm clamp bolt nut is locked in position a further check shows lost motion in the steering gear assembly a knowledge of the steering gear assembly is necessary before it can be adjusted here are the parts of the recirculating ball type steering gear this type assembly is used on the latest chevrolet 4x4 and gmc 6x6 vehicles the steering shaft worm gear is threaded with a precision finished helical groove tapered roller bearings are mounted at each end of the worm gear these adjustable bearings furnish a friction-free support for the shaft in the steering gear housing the ball nut surrounds the worm gear as shown on this cross-section ball nut a helical groove is threaded in the nut this groove corresponds to the groove on the worm gear ball bearings fill the passages formed by the grooves in the worm gear and nut tubular guides are fitted onto the nut to provide a passage for the ball bearings to return to their original positions the lower end steering gear housing plate is provided with a circular threaded opening the worm shaft bearing adjusting thrust screw is threaded into this opening the plug is turned until the shaft is just free of up and down play a locking nut is provided to lock the thrust screw in position when the worn shaft bearings are adjusted pitman arm shaft with its integral gear is straddle mounted in the steering housing suitable plane bearings in the housings on each side of the gear support this shaft in the housing when the steering shaft is turned the ball nut is moved back and forth by the recirculating passage of the ball bearings in the helical grooves the ball nut teeth engaging the sector gear teeth move the pitman arm shaft back and forth the mesh of the sector gear and ball nut teeth is also adjusted with an adjusting screw a locking nut is also provided to retain this adjusting screw in place the following procedure is employed to adjust the recirculating ball type of steering gear first the bracket which anchors the upper end of the steering column to the instrument panel is loosened this relieves any strain on the steering gear shaft that may be caused by misalignment of the jacket the steering connecting rod is then disconnected from the pitman arm this further relieves the steering gear assembly of strain the pitman shaft adjuster lock nut is loosened the lash adjustment screw is then turned counterclockwise a few turns to relieve the strain caused by close meshing of the sector and walnut gear teeth the worm gear bearings can now be adjusted to remove any lost motion caused by normal wear after the lock nut has been loosened the worm bearing thrust screw is turned clockwise until there is a slight drag on the steering wheel the lock nut is then tightened to determine whether the bearings are adjusted properly the steering wheel is moved one turn from the stop position the adjustment is then checked by rotating the wheel back and forth the wheel turns smoothly indicating that the adjustment is correct if any roughness is felt as the wheel is turned defective worm gear bearings are indicated and the steering gear should be replaced to remove lost motion between the gears it is first necessary to center the steering wheel the wheel is turned from one stop position to the other the number of turns being counted care is exercised to avoid hitting the stops too hard the wheel is then turned back halfway to a straight ahead position the pitman shaft thrust screw is adjusted until there's no lost motion between the worm gear and the sector teeth the lock nut is then tightened with the pitman shaft correctly adjusted the steering wheel is retested for load the load is now noticeably increased when testing equipment is available the bearing and gear load should be checked according to the manufacturer's specifications after these adjustments have been made any unevenness in operation is an indication of defective gears and the steering gear assembly should be replaced the steering column jacket is now checked to be sure it lines up with the dash supports in this instance the alignment is not satisfactory to realign the steering column jacket the bolts that attach the steering gear assembly to the frame are loosened this permits the steering gear assembly to shift and assume an aligned position then the instrument panel bracket is connected and the supporting u-bolt nuts are tightened securely the bolts attaching the steering gear assembly to the frame are re-tightened the drag link is then reconnected after these adjustments have been made the steering gear assembly is free of play and should operate satisfactorily you
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