TM 9-811 WAR DEPARTMENT TECHNICAL MANUAL 4-TON, 6x6 TRUCKS (DIAMOND T MODELS 968A CARGO, 969 A WRECKER, 970A PONTON, AND 972 DUMP) 25 JANUARY 1944(民國33年)《Black Water Museum Collections | 黑水博物館館藏》
WAR DEPARTMENT
Washington 25, D. C., 25 January 1944
TM 9-811, 4-ton, 6 x 6 Trucks (Diamond T Models 968A Cargo, 969A Wrecker, 970A Ponton, and 972 Dump) is published for the informa- tion and guidance of all concerned.
[A. G. 300.7 (3 June 43)]
BY ORDER OF THE SECRETARY OF WAR:
G. C. MARSHALL, Chief of Staff.
OFFICIAL:
J. A. ULIO,
Major General,
The Adjutant General.
DISTRIBUTION: X
(For explanation of symbols, see FM 21-6)
1. SCOPE.
a. *This technical manual is published for the information and guidance of the using arm personnel charged with the operation and maintenance of this materiel.
b. In addition to a description of the 4-ton, 6 x 6 truck (Diamond T, Models 968A Cargo, 969A Wrecker, 970A Ponton, and 972 Dump), this manual contains technical information required for the identifica- tion, use, and care of the materiel. The manual is divided into two parts. Part One, section I through section VIII, contains vehicle oper- ating instructions. Part Two, section IX through section XLIII, con- tains vehicle maintenance instructions for the using arm personnel charged with the responsibility of doing maintenance work within their jurisdiction.
c. In all cases where the nature of the repair, modifications, or adjustment is beyond the scope or facilities of the unit, the responsible ordnance service should be informed, so that trained personnel with suitable tools and equipment may be provided, or proper instructions issued.
*To provide operating instructions with the materiel, this technical manual has been published in advance of complete technical review. Any errors or omissions will be corrected by changes, or, if extensive, by an early revision.
2. DESCRIPTION.
a. General. The various models covered by this publication are all built on the same basic chassis, which is a 4-ton, 6 x 6 job, powered with a conventional six-cylinder gasoline engine. A five-speed overdrive transmission and a direct and underdrive transfer are used on all mod- els. All three axles are driving axles of conventional double-reduction design. Rear axles are dual-wheeled.
b. Identification. The four chassis are similar in appearance, and are built with open-type and closed-type cabs. These vehicles may be recognized by the design of the cabs, the contour of the fenders, and the appearance of the hood and radiator. The axle housings are clearly visible under the vehicle, and may be recognized as the banjo type. The vehicles may be positively identified by the nomenclature plate mounted on the left cowl side under the hood.
c. Differences among Models (figs. 1, 2, 3, and 4).
(1) CARGO TRUCK (MODEL 968A). The cargo truck is built on the standard 4-ton, 6 x 6 chassis. Special equipment consists of a stand- ard-type wooden cargo body with a tarpaulin top and troop seats, a power-driven, front-mounted winch, and two spare tires. The power take-off is mounted on the transmission.
(2) WRECKER TRUCK (MODEL 969A) (figs. 5, 6, 7, and 8). The wrecker truck is built on the standard 4-ton, 6 x 6 chassis. Special equipment consists of a steel wrecker body, twin boom power-driven wrecker equipment, welding tanks and equipment, a gasoline-driven air compressor unit, a power-driven front-mounted winch, and two spare tires. The power take-off which drives the wrecker equipment is mounted on the transfer, and the power take-off which drives the winch is on the transmission.
(3) PONTON TRUCK (MODEL 970A) (figs. 9 and 10). The ponton truck is built on a chassis which is the same as the standard 4-ton, 6 x 6 chassis, except that it has a longer wheelbase (par. 5). Special equip- ment consists of a standard-type wooden ponton body, with a tarpaulin top and a power-driven front-mounted winch. The power take-off is mounted on the left side of the transmission.
(4) DUMP TRUCK (MODEL 972) (figs. 11 and 12). The dump truck is built on the standard 4-ton, 6 x 6 chassis. Special equipment consists of a steel dump body, with power-driven hoist equipment. The power take-off for the hoist is mounted on the transfer case. There is no winch on this model.
DRIVING CONTROLS AND OPERATION
and the other on the steering wheel. He must be able to think and feel his truck. He must recognize any unnatural condition such as vibrations, scrapings, knocks, clicks, sluggishness, etc.
b. Preliminary Instructions. Before the engine is started, make the prestarting inspection outlined in paragraph 21. To start the engine, proceed as follows:
(1) Place transmission lever in neutral position.
(2) Set hand brake lever. (3) If the engine is cold, crack hand throttle about % open, and pull
choke button until it is half open. These steps may not be necessary when the engine is warm. If it is very cold, it may be necessary to choke the engine more.
(4) Turn on ignition.
(5) Push clutch pedal to floor and hold there until after engine is started.
(6) Press starter button.
(7) Release the starter button the moment the engine begins to run. Never press the starter button for more than 10 to 15 seconds at a time. If the engine has not started after two such trials, allow the starter to cool for one minute. If the engine fails to start, or makes a false start, do not press the starter button again until the engine has come to a complete stop. Failure to observe this precaution, especially after a false start, may result in a broken starter motor drive housing.
(8) After the engine has started, slowly release the clutch. Adjust the hand throttle to prevent the engine from racing. As soon as the engine runs smoothly, push the choke control. Excessive use of the choke will cause dilution of the engine oil and probable engine failure. During the engine warm-up period, operate the engine at 800 to 900 revolutions per minute as indicated by the tachometer. Idling is per- missible for only very short periods of time, not to exceed five minutes.
7. OPERATING THE VEHICLE.
a.Starting under Normal Conditions. After the engine has been thoroughly warmed up and checked for satisfactory operation, the vehicle may be started by following the steps listed below. NOTE: Be sure that sufficient air pressure (70 pounds per square inch as shown on dash gage) has been built up to provide adequate braking power (figs. 15 and 16).
(1) Push clutch pedal to the toeboard to completely disengage the clutch.
(2) Disengage the front axle drive by shifting the declutch lever as shown in the shifting diagram. (When extra traction is needed, en-gage front axle.)
(3) Shift transfer case lever into proper position. (Transfer case should be in low when heavily loaded, or when starting on a grade, and in high when unloaded or when starting on level ground.)
(4) Shift the transmission lever into first speed.
OPERATION OF AUXILIARY EQUIPMENT
9. WINCH.
a. General. A front-mounted winch is used on all cargo, wrecker and ponton vehicles. The winch is power-driven and may be used for pulling, hoisting or lowering. The winch is power-driven through a three-speed power take-off mounted on the side of the vehicle trans- mission. The driving torque is transferred from the power take-off through a propeller shaft with universal and slip joints to the winch drive shaft. The winch cable is 300 feet long, and has a safe pull capacity of 15,000 pounds on the first layer of cable. b. Operation. The winch is operated from inside the cab. It has an automatic safety brake which will sustain the load while the power take-off is being shifted. Winch pulling speeds are based on a maxi- mum engine speed of 1000 revolutions per minute, which should not be exceeded in winch operation, as excessive speed will result in strains and failures of parts. Note the instructions on the winch caution plate in the cab (fig. 18).
(1) HOOKING ON.
(a) Disengage the sliding jaw clutch by shifting the poppet handle mounted on the winch (fig. 22).
(b) Pull the cable off the drum by hand. The drag brake will keep the drum from spinning. Care should be exercised to avoid kinking the cable.
(c) Run the cable out to the load and hook on. Take care not to damage cable when hooking on. It is best to wrap a chain or cable around the load and to attach the winch cable to it.
(2) PULLING.
(a) Engage the sliding clutch, making sure that the poppets are locked.
the line. When cable is released it may be slacked sufficiently to unhook from loops in back of wrecker body so that it will be free for work at back of truck, or to swing with the boom when the latter is unlocked for rigging in position for work at an alongside position.
(2) Figure 25 identifies operating mechanism. The cable backlash brake loop is shown in brake applied position. Tension on the cable the brake through an eccentric. straightens it and, by pulling the loop into a vertical position, releases
(3) To free cable drum when running out the cable, the pinion shift lever is pushed in, and pulled out when it is desired to again engage the drum with the power mechanism.
(4) The booms are raised or lowered manually by the hand oper- ating crank on the end of the ratchet wheel shaft. The same crank may be used on the cable drum when tightening cable for traveling.
(5) The power operation of the winding (cable) drums can be con- trolled from either side, there being two handles on each side. The outer handles control the near drums, while the inner handles control the drums on the far side of the wrecker. The inner handles are also equipped with a sleeve which can be twisted to accelerate or decelerate the engine, similar to the throttle control on a motorcycle.
(6) APPLYING POWER (fig. 26).
(a) Shift transfer case lever into neutral.
(b) Shift transmission into direct speed, as normal operations can be carried out in this gear. All the speeds in the transmission may be used in wrecker operation except overdrive and reverse.
(c) Engage transfer case power take-off by pulling up the lever at the lower left of the control levers in cab, to engaged position as shown in figure 26. (d) The chain drive connecting the power take-off with the wrecker transmission main shaft is now in operation. To apply power to the cable drums for pulling or lowering, the load operator should stand on side nearest load. The control handles are held in neutral by a heavy spring so that as soon as pressure is released they return to neutral, stopping movement of drum and cable, the load being held by self- locking brake on worm shaft. To raise load, bear down on handle (fig. 25). To lower load, raise up on handle. Be sure that these shifts are made complete to prevent faulty engagement of the transmission. Speed of haul can be controlled by sleeve throttle control as previously described.
d. Cautions.
(1) Never run engine over 1800 revolutions per minute when operating wrecker. Never race the engine, especially when wrecker is operating without a load or with a very light load.
(2) Always use moderate speeds when pulling heavy loads until the load starts to move.
(3) When pulling over rough ground where possible use crowbars to ease load over rocks or other obstructions.
(4) Whenever possible to turn a wreck on its wheels this should be done as early in the operation as possible.
(5)Watch the cables to see they do not chafe on sharp edges.
(6) Keep cables free of kinks.
(7) Anchor lines must always be at least as strong as a service or hauling line.
(8) Cables should always be wound tight on drums. Wherever possible wind them up under load.
e. Safety Rings on Body Bolster (fig. 27).
(1) When the wrecker equipment is not in use, the ends of the cables should be hooked to the safety rings on the rear bolster of the body. These rings are designed so that if an excess tension is placed on the cables, the safety ring strap will open up and release the ring before damaging the body bolster.
f. Stowing Cable.
(1) In order to secure the proper tension on the cables when not in use, the truck transmission should be placed in one of the lower gears to slow down the cable speed and then by means of the winch-operating levers, the cable should be wound up until the backlash brake loop is moved forward until there is only 1/2-inch to 3/4-inch bend in the cable from top sheave to drum. This backlash brake loop serves as an excel- lent gage for the cable tension, and is in clear view of the operator.
(2) It is necessary that these cables be kept under a slight tension to prevent up-and-down movement of the booms on rough roads.
11. AIR COMPRESSOR (figs. 28 and 29).
a. Description. An independent air compressor unit is mounted on the wrecker body for use in tire inflation. The unit consists of a belt-driven compressor, a gasoline engine, an air reservoir, an automatic cut-off switch, a check valve, a safety valve and a pressure gage. The cut-off switch automatically shuts off the engine when the reservoir pressure reaches 150 pounds per square inch. The check valve prevents air in the reservoir from flowing back when the compressor stops.
b. Operating Suggestions.
(1) BELT TENSION. The belt should be kept in proper adjustment at all times. When adjusting belts be sure pulleys are properly lined up. Belts should be just tight enough to prevent slippage. Heating of motor pulley indicates slipping.
