TM-9-2520-234-35 Technical Manual for M109 Transmission XTG-411-2A Download

PAR 23-25 DESCRIPTION AND OPERATION OF CHAP 2, SEC II MAIN TRANSMISSION ASSEMBLY is the driving member. It meshes with and drives gear 14. Gear 14 rotates on a needle bearing 13, and is supported by shaft 10. Gear 11 rotates on needle bearings 7 and 17, supported by body 8 and cover 19. Ball 9 anchors shaft 10 against rotation. Pins 18 and screws 15 aline and retain cover 19. (2) The pump assembly mounts in the converter housing near the transmis- sion left-output coupling. Four self-locking bolts 1 retain it. The pump is driven by a gear splined to the transmission output shaft and in mesh with gear 5, which is keyed to gear 11. b. Operation (fig. 384, fold-out 13) (1) This pump assembly is a con- ventional spur gear type. It supplies oil to the hydraulic system when the vehicle is moving forward. In reverse, a spring- loaded check valve 63 (fig. 374, fold-out 3) prevents oil from returning to the in- take side of the pump. (2) The oil pumped augments that supplied by the input-driven pump. It is the only source of oil pressure if the ve- hicle is towed or pushed while the engine is not operating. 24. BRAKE COOLANT OIL PUMP ASSEMBLY AND MANIFOLD a. Components (fig. 384, fold-out 13) (1) The pump assembly includes drive gear 49, shaft 40, two gears 21 and 26, two gears 33 and 43, shaft 22, separa- tor plate assemblies 23 and 36, cover assembly 44, body 32 and cover assembly 28. The gears and shafts are steel. The body and covers are cast iron. (2) The pump consists of two se- parate pumping sections — one for each of the brakes. Each pump has a separate pair of gears. A common housing and common shafts serve both pump sections. The pairs of gears are separated by two plate assemblies 23 and 36. Driving gears 33 and 43 are keyed to shaft 40. Idler gears 21 and 26 are not keyed. Shafts 22 and 40 each rotate on three needle bear- ing assemblies. (3) Manifold 56 serves as a base and mounting pad for the pump assembly. The manifold includes passages for separ- ate intake ports for each pump section and provides m cans for two intake check valves. b. Operation (fig. 384, fold-out 13) — (1) The pump is driven by a gear splined to the low-range carrier shaft and in mesh with gear 53 (fig. 379, fold-out 8), which, in turn, drives gear 49 (fig. 384, fold-out 13). The pump rotates any time the vehicle moves. During forward move- ment, when brakes are released, air is drawn into the pump through open air valves (refer to par. 18b(2), above). During reverse movement (brakes released), air is expelled through the air valves. (2) When brakes are applied, the air valves are closed. The pump then draws oil through check valve washer assembly 67. Each section of the pump then delivers oil to a brake. The right section supplies the right brake; the left section supplies the left brake. 25. OIL FILTER AND SCREENS a. Components (fig. 373 and 374, — Told-outs 2 and 3) (1) All oil in the system must pass through screens before it is directed into its various circuits. The scavenge pump must draw oil through screen 107 (fig. 373, fold-out 2) before returning it to the transmission sump. The input- and output-driven pressure pumps draw oil through screen assembly 23 (fig. 374, fold-out 3) before sending it into the system. The brake coolant pump must draw oil through the same screen. These two screens are simple, cylindrical wire mesh screens. (2) Oil filter assembly (fig. 153), capable of screening finer particles from the oil, is located in the circuit which di- rects the output of the pressure oil pumps into the hydraulic system. The assembly includes a filter head assembly and filter element. Change 2 23