TM 9-1727D TRANSFER UNIT FOR LIGHT TANKS M5, M5A1, AND 75-MM HOWITZER MOTOR CARRIAGE M8, APRIL 28, 1943
民國32年，TM 9-1727D，M5, M5A1輕戰車及M8砲車傳動箱技術手冊《Black Water Museum Collections | 黑水博物館館藏》
1. PURPOSE AND SCOPE.
a. TM 9-1727D is published for the information and guidance of all ordnance personnel charged with the maintenance and overhauling of Light Tanks M5, M5A1, and 75-mm Howitzer Motor Carriage M8. It includes complete maintenance information on the transfer unit. The other technical manuals covering these vehicles are listed in section IIIL
2. DESCRIPTION OF VEHICLES.
a. The Light Tanks M5 and M5A1 are armored, full-tracklaying combat vehicles, each carrying a crew of four men. They are each powered by two liquid-cooled, 90-degree, V-type, 8-cylinder engines, located in the engine compartment in the rear of the hull. Power is transmitted to the final drives and tracks through two Hydra-Matic transmissions, two propeller shafts, a two-speed, step-down transfer unit, and the controlled differential (fig. 4).
b. The Motor Carriage M8 (fig. 3) is an armored, full-tracklaying, self-propelled mount for a 75-mm howitzer. It carries a crew of four men. It is powered by the same engines, transmissions, and power train as the Light Tank M5.
3. REFERENCES. a. Section III of this volume lists all technical manuals, standard nomenclature lists, and other publications relative to the materiel described herein.
4. DESCRIPTION.
a. The transfer unit performs two distinct functions. It takes the power of the two engines, delivered to the transfer unit by he propeller shafts, and combines these two power flows into one. It also provides a two-speed, hydraulic-controlled gear reduction which, combined with the reductions in the transmissions, permits a total of six forward speeds and one reverse speed.
b. The transfer unit is located in the front end of the vehicle, mounted on a flange on the rear of the controlled differential housing (fig. 5).
c. The transfer unit case is composed of two sections, a large main case at the front which contains the mechanism for the gear reduction unit and the hydraulic control parts, and a smaller case at the rear which contains the connector unit by means of which the torque from the two propeller shafts is combined into the one transfer unit main shaft.
d. The connector gears which combine the torque are all of the same diameter and thus do not provide any reduction. The connector gear shafts are mounted in the case in single row ball bearings. The main shaft or input shaft into the transfer unit proper is mounted at its rear- ward end on a double row ball bearing and on its forward or inner end on a roller pilot bearing (L, fig. 6) in the counterbore of the transfer unit output shaft.
e. The spiral drive pinion for the controlled differential is splined to the transfer unit output shaft and held securely in place by a cottered castle nut. The forward or pinion end of the output shaft is mounted in the transfer case on a large, double-row ball bearing, and the rearward or inner end on a single-row ball bearing.
f. The gear reduction unit is a compound planetary system with the two center gears integral with the main shaft, and the second planet carrier attached to the output shaft. Two bands are used to lock the brake drum and thus provide reduction. The low gear band is selfenergizing in forward speeds and the reverse band, in reverse speeds. A multiple disk clutch, engaged by oil pressure, is contained in the clutch drum assembly, and locks the planetary gear train as a unit to provide direct drive.
g. The servos which apply and release the two bands are mounted on the top of the main transfer unit case (figs. 7 and 8). The oil pumps and governor are mounted on a carrier located on the right-hand side of the unit, and the valves which control the shifting are mounted in a valve body on top of the unit.
5. OPERATION.
a. Reduction. When the vehicle is started or operated at low speeds, the transfer unit is in reduction (fig. 10). The low gear band is applied to the drum by spring pressure in the low gear servo, and the clutch is released because there is no oil pressure to the clutch apply pistons. The reverse servo is released by oil pressure applied to the release piston and in held in the released position by a mechanically-operated latch and a ball check valve which prevents air from being drawn into the system. As the main shaft is rotated, the two center gears, being integral with the shaft, also rotate. The internal gear for the first planetary gear train is held from rotating by the low gear band; consequently, the planet gears in this train "walk around" inside the internal gear and carry the planet carrier at speed less than that of the first center gear. The planet carrier for the first planetary gear train is integral with the internal gear for the second planetary train; consequently, this internal gear rotates
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