Systems Operation Introduction Reference: For illustrated Specifications, refer to the Specifications For 416, 426, 428, 436, 438, & Series II Backhoe Loaders Transmission, Form No. SENR3131. If the specifications in Form No. SENR3131 are not the same as in the Systems Operation and the Testing and Adjusting, look at the date on the back cover of each book. Use the specifications given in the book with the latest date. General Information Components Of The Power Train (1) Engine. (2) Flywheel. (3) Torque converter. (4) Transmission. Power from diesel engine (1) is sent from the flywheel to torque converter (3) through a conventional flex drive plate arrangement. A pilot bore in the flywheel provides alignment for the front end of the converter during installation. Torque converter (3) features a freewheel clutch that allows the converter stator to freewheel during high speed, low load conditions, such as roading the machine. A freewheeling stator changes the converter into a fluid coupling for better efficiency at the high speed end.
Transmission (4) features a manual four-speed, direct-drive helical gear, constant mesh, synchronized arrangement, coupled with hydraulically shifted, forward and reverse shuttle clutches. Transmission Transmission Hydraulic System In Neutral (Engine Running - Type 1 Control Valve Shown) (1) Forward clutch assembly. (2) Reverse clutch assembly. (3) Input shaft assembly. (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer solenoid. (7) Flow control spool. (8) Forward/reverse selector valve. (9) Oil filter. (10) Load piston. (11) Oil pump. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (15) Inlet relief valve for
torque converter. (16) Screen. (17) Oil cooler. (18) Oil reservoir. (19) Torque converter. (20) Orifice for torque converter bypass. (A) Pressure tap for reverse clutch. (B) Pressure tap for pump. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (E) Pressure tap for torque converter outlet. (F) Pressure tap for lubrication and cooling.
Transmission Hydraulic System In Forward (Engine Running - Type 2 & 3 Control Valve Shown) (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer solenoid. (7) Flow control spool. (8) Forward/reverse selector valve. (9) Oil filter. (10) Load piston. (11) Oil pump. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (15) Inlet relief valve for torque converter. (16) Screen. (17) Oil cooler. (18) Oil reservoir. (19) Torque converter. (20) Orifice for torque converter bypass. (21) Orfice. (22) Supply passage to 4-WD clutches. (23) Orfice. (24) Relief valve (4-WD only). (25) Transmission lubrication system. (A) Pressure tap for reverse clutch. (B) Pressure tap for pump. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (E) Pressure tap for torque converter outlet. (F) Pressure tap for lubrication and cooling. (G) Pump oil. (H) Return oil. (J) Converter inlet oil. (K) Supply oil. (L) Converter outlet oil. (M) Lubrication oil. Torque Converter The torque converter hydraulically connects the engine to the transmission. There is no direct mechanical connection between the engine and the transmission. When the machine works against a load, the torque converter can multiply the torque from the engine and send a higher torque to the transmission. The oil for the operation of the torque converter comes from transmission oil pump (11). The oil flows to externally mounted transmission control valve (4). Oil flow is divided at flow control spool (7). Oil is directed to the transmission circuit and to the torque converter circuit. The torque converter inlet oil pressure is controlled by relief valve (15). Converter inlet relief valve (15) is mounted in the valve adapter (manifold) mounted below transmission control valve (4). The relief valve limits the pressure to torque converter (19) to 750 kpa (110 psi). Outlet oil from the converter flows through transmission oil cooler (17) and into the lubrication and cooling system. Location Of Converter Inlet Relief Valve
Torque Converter (26) Turbine. (27) Stator. (28) Impeller. (29) Housing. (30) Flex plate. (31) Stator clutch. The torque converter has four main parts: housing (29), impeller (pump) (28), turbine (26) and stator (27). The housing is connected to the engine flywheel through flex plate (30). Impeller (28) and housing (29) are connected and turn with the engine flywheel at engine speed. Turbine (26) turns the transmission input shaft. Stator (27) is installed stationary on stator support (not shown). Impeller (28), which turns with housing (29) at engine speed, directs the oil toward the outside of the impeller and against the blades of turbine (26). When the oil hits the turbine blades, it causes turbine (26) and transmission input shaft (3) to turn. This sends torque to the transmission. Oil returns through the stator vanes to the impeller. The stator vanes direct the oil back to the impeller, which causes a torque increase. When the speed of turbine (26) is the same as the speed of impeller (28), stator clutch (31) permits the stator to turn freely with engine rotation for more efficient operation. When turbine torque is greater than impeller torque the stator is locked in place. Torque is multiplied only when the stator is held in place. Transmission
Transmission (1) Input shaft assembly. (2) Forward input gear. (3) Forward clutch pack. (4) Forward clutch piston. (5) Reverse clutch piston. (6) Reverse clutch pack. (7) Reverse input gear. (8) Forward driven gear. (9) Countershaft. (10) Reverse idler shaft. (11) Reverse idler driven gear. (12) Reverse idler input gear. (13) Output shaft. (14) Front wheel drive input gear (4-wheel drive only). (15) First speed gear. (16) First and second speed synchronizer assembly. (17) Second speed gear. (18) Third speed gear. (19) Third and fourth speed synchronizer assembly. (20) Fourth speed gear.
Transmission Shaft Locations (1) Input shaft assembly. (9) Countershaft. (10) Reverse idler shaft. (13) Output shaft. The transmission features a manual four-speed, direct-drive helical gear, constant mesh, synchronized arrangement, coupled with hydraulically shifted forward and reverse shuttle clutches. The shuttle is a multi-disc clutch arrangement with two clutch packs contained within the input shaft assembly. Each clutch pack contains six plates and six discs. The clutches are engaged hydraulically and released by spring force. For serial numbers 3DJ1-UP, 5PC3697-UP, 7BC691-UP, 6TC648-UP and 5KF1-UP each clutch pack contains seven plates and six discs. To make the vehicle move, the clutch engagement is done through a mechanical linkage connected to the hydraulic control valves, forward/reverse selector valve. This hydraulically engages forward clutch (3) or reverse clutch (6). Input shaft assembly (1) sends the power from the torque converter turbine to the forward/reverse shuttle clutches. The input shaft assembly rotates the same direction as the flywheel. Therefore, the plates also rotate the same direction at the same speed as the input shaft. The input shaft assembly also provides three internal oil passages. One passage is for lubrication and cooling of the shuttle. The other two passages are for engaging the forward or reverse clutch packs. One passage for forward and the other for reverse. Forward input gear (2) and reverse input gear (7) are free to rotate on the input shaft assembly when the clutch packs are not engaged. The discs rotate with the input gears. Reverse idler shaft (10) and gears (11) and (12) provide reverse rotation to countershaft (9) when the reverse clutch is engaged. Reverse idler driven gear (11) is engaged with reverse input gear (7). The power flows from the reverse idler driven gear to reverse idler input gear (12) when reverse clutch pack (6) is engaged. Countershaft (9) transfers power to the speed range gears on output shaft (13) either from forward input gear (2) or from reverse idler input gear (12), depending on which clutch pack is engaged. Output shaft (13) carries speed range gears (15), (17), (18) and (20) and synchronizer assemblies (16) and (19). All but one of the speed range gears rotate on fluted areas, which are for lubrication purposes. First speed gear (15) is supported by needle bearings.
Synchronizer Assembly (Shown in NEUTRAL) (22) Cup. (23) Fork. (24) Sliding collar. (25) Pin. (26) Split pin. (27) Cone. The synchronizer assembly consists of two inner synchronizer cones (27). The cones are mounted to sliding collar (24) by a series of alternating alignment blocker pins (25) and spring loaded split pins (26). The inner diameter of sliding collar (24) is splined to output shaft (13). The speed range gears have matching splines. Synchronizer cups (22) are splined to the speed range gears, thus rotate with the speed range gears. When shifter fork (23) moves sliding collar (24) to engage a speed gear, the collar comes in contact with the shoulder on the blocker pins. The force exerted on the pins causes it to push the cone against the cup. Now the sliding collar assembly and output shaft are rotating at the same speed as the speed gear, thus synchronization has occurred. If there is a torsional load or mismatch of speeds between the speed range gear and the output shaft, the blocker pin shoulder will hold the collar from engaging. When the speeds are synchronized and there is no torsional or side load on the blocker pin, the sliding collar will continue to slide as the shifter fork moves it. The spring loaded split pins will collapse and act as a locking mechanism to keep the sliding collar and output shaft engaged. The four speed shift lever is on the floor. To shift speed range gears, the operator neutralizes the transmission by depressing the neutralizer button on the shift lever and holds it. Once the transmission is in NEUTRAL, the operator can engage any speed range gear, even while the vehicle is moving. Once the shift has been done, the neutralizer button is released. Only one synchronizer assembly can be engaged at a time.
Power Flows First Or Second Speed Forward Synchronizer Assembly (Shown in NEUTRAL) (22) Cup. (23) Fork. (24) Sliding collar. (25) Pin. (26) Split pin. (27) Cone.
Power Flow In First Speed Forward (1) Input shaft assembly. (2) Forward input gear. (3) Forward clutch pack. (4) Forward clutch piston. (5) Reverse clutch piston. (6) Reverse clutch pack. (7) Reverse input gear. (8) Forward driven gear. (9) Countershaft. (13) Output shaft. (14) Front wheel drive input gear (4-wheel drive only). (15) First speed gear. (16) First and second speed synchronizer assembly. (17) Second speed gear. (18) Third speed gear. (19) Third and fourth speed synchronizer assembly. (20) Fourth speed gear. The torque converter turbine drives input shaft assembly (1). To engage the forward clutch, the operator moves the direction control lever, mounted on the steering wheel column, to the forward position. This causes oil pressure to be sent through input shaft assembly (1) to pressurize forward clutch piston (4). Forward clutch pack (3) is engaged and sends the power to forward input gear (2). Forward input gear (2) transmits the power to forward driven gear (8), which turns countershaft (9), which is constantly engaged with the speed range gears. For first or second speed gear to be engaged with the output shaft, the neutralizer button, located on the shift lever, must be activated to dump directional clutch and put the transmission in NEUTRAL. Now the shift lever can be moved to first or second gear. Shifter fork (23) slides synchronizer collar (24) to the left so first gear (15) engages with output shaft (13), or to the right so second speed gear (17) engages with output shaft (13). If the speed of the speed gear and the output shaft are the same and there is no torsional loads, synchronizer assembly (16) will engage the speed gear with the
output shaft. Once the shift is complete the neutralizer button must be deactivated (released). The shift is completed and the directional clutch is engaged. Power is now being sent to the differential. Third Or Fourth Speed Forward The torque converter turbine drives input shaft assembly (1). To engage the forward clutch, the operator moves the direction control lever, mounted on the steering wheel column, to the FORWARD position. This causes oil pressure to be sent through input shaft assembly (1) to pressurize forward clutch piston (4). Forward clutch pack (3) is engaged and sends the power to forward input gear (2). Forward input gear (2) transmits the power to forward driven gear (8), which turns countershaft (9) which is constantly engaged with the speed range gears. For third or fourth speed gear to be engaged with output shaft (13), the neutralizer button, located on the shift lever, must be activated to dump directional clutch and put the transmission in NEUTRAL. Now the shift lever can be moved to third or fourth gear. Shift fork (23) slides the synchronizer collar (24) to the left so third speed gear (18) engages with output shaft (13) or to the right so fourth speed gear (20) engages with output shaft (13). If the speed of the speed gear and the output shaft are the same and there is no torsional loads, synchronizer assembly (19) will engage the speed gear with the output shaft. Once the shift is complete the neutralizer button must be deactivated (released). The shift is completed and the directional clutch is engaged. Power is now being sent to the differential. First Or Second Speed Reverse Synchronizer Assembly (Shown in NEUTRAL) (22) Cup. (23) Fork. (24) Sliding collar. (25) Pin. (26) Split pin. (27) Cone.
The torque converter turbine drives input shaft assembly (1). To engage the reverse clutch, the operator moves the direction control lever, mounted on the steering wheel column, to the REVERSE position. This causes oil pressure to be sent through input shaft assembly (1) to pressurize reverse clutch piston (5). Reverse clutch pack (6) is engaged and sends power to reverse input gear (7). The reverse input gear transmits the power to reverse idler driven gear (11), which turns reverse idler shaft (10) and reverse idler input gear (12). The reverse idler input gear transmits the power to the countershaft (9). The countershaft will rotate in the opposite direction as it would in forward, which gives the reverse direction. The countershaft is in constant mesh with the speed range gears mounted on output shaft (13). For first or second speed gear to be engaged with the output shaft, the neutralizer button, located on the shift lever, must be activated to put the transmission in NEUTRAL. Now the shift lever can be moved to first or second gear. Shift fork (23) slides synchronizer collar (24) to the left so first speed gear (15) engages with output shaft (13) or to the right so second speed gear (17) engages with output shaft (13). If the speed of the speed gear and the output shaft are the same and there is no torsional loads, synchronizer assembly (16) will engage the speed gear with the output shaft. Once the shift is complete the neutralizer button must be deactivated (released). The shift is completed and the directional clutch is engaged. Power is now being sent to the differential. Third Or Fourth Speed Reverse
Power Flow In Third Speed Reverse (1) Input shaft assembly. (2) Forward input gear. (3) Forward clutch pack. (4) Forward clutch piston. (5) Reverse clutch piston. (6) Reverse clutch pack. (7) Reverse input gear. (8) Forward driven gear. (9) Countershaft. (10) Reverse idler shaft. (11) Reverse idler driven gear. (12) Reverse idler input gear. (13) Output shaft. (14) Front wheel drive input gear (4-wheel drive only). (15) First speed gear. (16) First and second speed synchronizer assembly. (17) Second speed gear. (18) Third speed gear. (19) Third and fourth speed synchronizer assembly. (20) Fourth speed gear. The torque converter turbine drives input shaft assembly (1). To engage the reverse clutch the operator moves the direction control lever, mounted on the steering wheel column, to the REVERSE position. This causes oil pressure to be sent through input shaft assembly (1) to pressurize reverse clutch piston (5). Reverse clutch pack (6) is engaged and sends power to reverse input gear (7).
The reverse input gear transmits the power to reverse idler driven gear (11), which turns reverse idler shaft (10) and reverse idler input gear (12). The reverse idler input gear transmits the power to countershaft (9). The countershaft will rotate in the opposite direction it would in forward, which gives the reverse direction. The countershaft is in constant mesh with the speed range gear mounted on output shaft (13). For third or fourth speed gear to be engaged with the output shaft, the neutralizer button, located on the shift lever, must be activated to put the transmission in NEUTRAL. Now the shift lever can be moved to third or fourth gear. Shift fork (23) slides synchronizer collar (24) to the left so third speed gear (18) engages with output shaft (13) or to the right so fourth speed gear (20) engages with output shaft (13). If the speed of the speed gear and the output shaft are the same and there is no torsional loads, the synchronizer will engage the speed gear with the output shaft. Once the shift is complete the neutralizer button must be deactivated (released). The shift is completed and the directional clutch is engaged. Power is now being sent to the differential.
Transmission Hydraulic System In Neutral (Engine Running - Type 1 Control Valve Shown) (1) Forward clutch assembly. (2) Reverse clutch assembly. (3) Input shaft assembly. (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer solenoid. (7) Flow control spool. (8) Forward/reverse selector valve. (9) Oil filter. (10) Load piston. (11) Oil pump. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (15) Inlet relief valve for torque converter. (16) Screen. (17) Oil cooler. (18) Oil reservoir. (19). Torque converter. (20) Orifice for torque converter bypass. (A) Pressure tap for reverse clutch. (B) Pressure tap for pump. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (E) Pressure tap for torque converter outlet. (F) Pressure tap for lubrication and cooling.
Transmission Hydraulic System Transmission Hydraulic System In Forward (Engine Running - Type 2 & 3 Control Valve Shown)
(4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer solenoid. (7) Flow control spool. (8) Forward/reverse selector valve. (9) Oil filter. (10) Load piston. (11) Oil pump. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (15) Inlet relief valve for torque converter. (16) Screen. (17) Oil cooler. (18) Oil reservoir. (19) Torque converter. (20) Orifice for torque converter bypass. (21) Orfice. (22) Supply passage to 4-WD clutches. (23) Orfice. (24) Relief valve (4-WD only). (25) Transmission lubrication system. (A) Pressure tap for reverse clutch. (B) Pressure tap for pump. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (E) Pressure tap for torque converter outlet. (F) Pressure tap for lubrication and cooling. (G) Pump oil. (H) Return oil. (J) Converter inlet oil. (K) Supply oil. (L) Converter outlet oil. (M) Lubrication oil. The basic components of the hydraulic system for operation of the transmission and torque converter are: oil reservoir (18), oil screen (16), oil pump (11), oil filter (9), torque converter (19), flow control spool (7), relief valve (12), load piston (10) for shift modulation, check valve (13) for load piston, forward/reverse selector valve (8), neutralizer valve (5), neutralizer solenoid (6), relief valve (15) for converter inlet, oil cooler (17), forward clutch pack (1) and reverse clutch pack (2). All oil passages are inside the transmission case and transmission control valve (4) body, except the two transmission hydraulic lines connected to oil cooler (17). From serial number 3DJ1-UP, 5PC4451-UP, 7BC1163-UP, 6TC1364-UP and 5KF1-UP, an external tube provides an oil passage from the relief valve passage to the neutralizer valve passage. Torque Converter, Transmission Pump, Screen And Filter The oil for the operation, cooling and lubrication of the transmission and torque converter is made available by an internal gear pump. The pump is located at the transmission input shaft. The torque converter stator support and pump are assembled together and the assembly is bolted to the transmission case. The pump is driven by the torque converter impeller housing. The oil reservoir for the transmission and torque converter is in the bottom of the transmission case. Oil from the reservoir flows through the pipe assembly to the screen and through the transmission case passages to the suction side of the positive displacement pump. The oil from the pump flows to the filter and then the transmission hydraulic controls. If there is a restriction in the oil filter or if the viscosity of the oil is very high, the bypass valve in the filter housing will open. If the inlet pressure to the oil filter is 117 to 131 kpa (17 to 19 psi) greater than the outlet pressure, the bypass valve will open. When the oil does not go through the filter element, unfiltered oil could cause damage to other components in the hydraulic system. Correct maintenance must be used to make sure that the element does not become plugged and stop the flow of clean oil to the hydraulic system. The filter is mounted to the left side of the transmission case. The screen is mounted inside the transmission case. The screen can be removed on the right side of case. Location Of Oil Filter
Location Of Screen (Behind Plug Assembly) Power Train Oil Cooler The power train oil cooler is mounted in the bottom tank of the radiator. System oil with high temperature comes from the torque converter outlet. This oil goes in one side of the core assembly. The flow of oil is through the core assembly, as coolant flows around the core assembly. In this way, heat is removed from the oil and is given to the coolant. After the oil flows through the cores, it goes out through the outlet passage at the other end of the core assembly and has a lower temperature. The cooler oil then goes to the transmission lubrication and cooling.
Location Of Power Train Oil Cooler Transmission Lubrication System
Transmission Lubrication The only pressure lubrication in the transmission is for the forward and reverse shuttles, discs, plates and bearings. After the oil has been cooled by the oil cooler, the oil will enter the right side of the transmission case and go to the right end of the input shaft. Oil flows down the oil passages in the shaft and cools and lubricates the bearings, plates and discs. The other gears and bearings are splash lubricated. The movement of the gears in the oil reservoir causes oil to be thrown on all components. Hydraulic Controls NOTE: Serial number breaks for the different types of control valves are: Type 1; 5PC1-5PC4450, 7BC1-7BC1162, and 6TC1-6TC1363. Type 2; 3DJ1-3DJ173, 5PC4451-5PC8078, 7BC1163-7BC2628, 6TC1364-6TC4297 and 5KF1-5KF466. Type 3; 3DJ157-UP, 5PC8079-UP, 7BC2629-UP, 6TC4297-UP and 5KF467-UP. Location Of Transmission Hydraulic Controls
The torque converter inlet oil pressure is limited by relief valve (15) mounted in the valve adapter. The valve adapter is mounted between the control valve and the transmission case. The relief valve limits the pressure to the torque converter to 750 kpa (110 psi) The transmission hydraulic controls are installed on top of the transmission case. Inlet oil to operate the hydraulic controls comes from oil filter (9). Flow control spool (7) provides a predetermined maximum flow rate to the transmission circuit and bypasses excess flow to the torque converter circuit. The orifice down the center of the spool provides the oil for the transmission circuit. The flow control spool position will change to maintain needed flow through the control valve as load changes. Location Of Neutral/Start Switch Forward/reverse selector valve (8) rotates to direct pressurized oil to the forward or reverse clutch pistons or to drain if in NEUTRAL. The selector valve also allows the clutch pistons to drain if they are not engaged. The selector valve also activates and deactivates the neutral/start switch. If the selector valve is left in a forward or reverse position when the vehicle is turned off, the selector valve will deactivate the neutral/start switch so the vehicle cannot be started until the selector valve is returned to the neutral position at next start-up. The forward/reverse selector valve is mechanically actuated by a mechanical linkage and the direction control lever mounted on the steering wheel column. Location Of Direction Control Lever Neutralizer valve (5) and neutralizer solenoid (6) are used when the transmission is to have a speed change or full horsepower is required at the loader hydraulics.
Location Of Neutralizer Button On Shift Lever Location Of Neutralizer Button On Loader Lever The neutralizer solenoid is controlled by two neutralizer button switches. One switch is located on the gear shift lever and the other on the loader lever. To activate the neutralizer solenoid, the neutralizer button switch would be pushed in and held until the shift is complete or the loader function is complete. The button is released to deactivate the neutralizer solenoid. When the neutralizer solenoid is activated a rod extends to the left, moving neutralizer valve (5) to the left too. As the neutralizer valve moves to the left a drain port is opened, allowing most pressurized oil for the transmission circuit to go to the drain (reservoir). The oil pressure in the directional clutch circuit decreases and the directional clutch disengages. When the neutralizer solenoid is deactivated the rod retracts and the spring returns the neutralizer valve, closing the drain port, refilling the directional clutches and allowing the transmission to gain pressure again. Do not operate the engine at high idle speed with cold transmission oil. The cold oil may prevent the neutralizer valve from functioning properly and the machine could move. The modulating relief valve consists of relief valve (12) and load piston (10). The modulating relief valve provides a variable relief valve, controls the rate pressure rises in the forward or reverse clutch pack and limits maximum clutch pressure. Orifice (14), in the cover for load piston (10), controls the rate the load piston engages. Check valve (13) allows the load piston to dump oil rapidly.
Transmission Hydraulic System In Neutral (Engine Running - Type 1) (1) Forward clutch assembly. (2) Reverse clutch assembly. (3) Input shaft assembly. (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer solenoid. (7) Flow control spool. (8) Forward/reverse selector valve. (9) Oil filter. (10) Load piston. (11) Oil pump. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (15) Inlet relief valve for torque converter. (16) Screen. (17) Oil cooler. (18) Oil reservoir. (19) Torque converter. (20) Orifice for torque converter bypass. (A) Pressure tap for reverse clutch. (B) Pressure tap for pump. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (E) Pressure tap for torque converter outlet. (F) Pressure tap for lubrication and cooling. Operation
Starting The Engine (Transmission in Neutral) Transmission Hydraulic Control Valve (Type 2) (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer valve. (7) Flow control spool. (8) Forward/reverse selector valve. (10) Load piston. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (23) Orfice. (A) Pressure tap for reverse clutch. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (G) Pump oil. (H) Return oil. (J) Converter inlet oil. When the engine is started oil pump (11) pulls oil from reservoir (18) through screen (16) to the pump. The pump sends the oil through filter (9) to control valve (4). Orifice (23) allows oil pump to bleed air to tank during initial start up. Orifice (23) also provide additional oil flow to the torque converter with out passing through flow control valve (7). Oil pressure moves flow control spool (7) to the right. This allows oil not needed by the transmission circuit to flow to the torque converter circuit. On the machines with type 1 control valves, oil needed by the transmission circuit flows through the orifice in the center of flow control (7) spool and goes to forward/reverse selector valve (8).
On the type 2 control valve machines, oil needed by the transmission circuit, flows through the orifice in the center of flow control spool (7) and goes to the neutralizer valve (5), through the external tube. Then, the oil goes to the forward/reverse selector valve (8). In NEUTRAL, the selector valve directs oil flow to the reservoir (drain), thus neither forward or reverse clutch pack can be pressurized. The clutch oil passages are open to drain. Since neutralizer solenoid (6) has not been activated, nothing occurs at neutralizer valve (5). With the forward/reverse selector valve in neutral there is low residual pressure within the control valve. So little pressure is sent to load piston (10) for modulation. Relief valve (12) pressure may be as low as initial relief setting. Transmission Hydraulic Control Valve (Type 3) (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer valve. (7) Flow control spool. (8) Forward/reverse selector valve. (10) Load piston. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (23) Orfice. (A) Pressure tap for reverse clutch. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (G) Pump oil. (H) Return oil. (J) Converter inlet oil. On the type 3 control valve machines, oil needed by the transmission circuit, flows through the orifice in the center of flow control spool (7) and goes to the neutralizer valve (5), through the external tube. Then, the oil goes to the forward/reverse selector valve (8). In NEUTRAL, the selector valve blocks oil flow, thus neither
forward or reverse clutch pack can be pressurized. The clutch oil passages are open to drain. Since neutralizer solenoid (6) has not been activated, nothing occurs at neutralizer valve (5). With the forward/reverse selector valve in neutral there is full oil pressure built up within the control valve. So pressure is sent to load piston (10) for modulation. Relief valve (12) maintains full relief pressure. Transmission Hydraulic System In Forward (Engine Running - Type 1) (1) Forward clutch assembly. (2) Reverse clutch assembly. (3) Input shaft assembly. (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer solenoid. (7) Flow control spool. (8) Forward/reverse selector valve. (9) Oil filter. (10) Load piston. (11) Oil pump. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (15) Inlet relief valve for
torque converter. (16) Screen. (17) Oil cooler. (18) Oil reservoir. (19) Torque converter. (20) Orifice for torque converter bypass. (A) Pressure tap for reverse clutch. (B) Pressure tap for pump. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (E) Pressure tap for torque converter outlet. (F) Pressure tap for lubrication and cooling. Engine Running (Neutral To Forward) Transmission Hydraulic Control Valve (Type 2 And Type 3) (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer valve. (7) Flow control spool. (8) Forward/reverse selector valve. (10) Load piston. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (A) Pressure tap for reverse clutch. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (G) Pump oil. (H) Return oil. (J) Converter inlet oil. When the direction control lever on the steering wheel column is moved to the forward position (away from the driver), the linkage moves forward/reverse selector valve (8) to the forward position. With the engine running, oil pump (11) pulls oil from reservoir (18), through screen (16), to the pump. The pump sends the oil through filter (9) to the control valve. Oil pressure moves flow control spool (7) to the right. This allows oil not needed by the transmission circuit to flow to the torque converter circuit.
Oil needed by the transmission circuit flows through the orifice in the center of the flow control spool and goes to forward/reverse selector (8). With the selector valve in the forward position, oil is directed to forward clutch assembly (1). The reverse clutch oil passage is open to drain. Oil fills the forward clutch and then modulation occurs. Orifice (21) maintains oil pressure to 4-WD clutches when oil pressure drops during transmission directional clutch shifts. The function of modulating relief (12) valve and load piston (10) is to control the rate of the pressure increase in the directional clutch circuit and limit the final clutch pressure as follows for smooth engagement of the clutch. As the pressure in the transmission circuit increases, relief valve (12) starts to move to the right and load piston (10) starts to move to the left. Orifice (14), in the supply passage to the load piston, causes the oil to go to the area behind the load piston at a specific rate. As the relief valve moves to the right and the load piston to the left, the pressure in the forward clutch assembly increases gradually. This gradual increase in pressure is known as modulation. When the load piston reaches its full stroke the relief valve will relieve excess flow to the reservoir and maximum system pressure is reached. Since neutralizer solenoid (6) has not been activated nothing occurs to change the clutch engagement. Engine Running (Forward To Reverse) When the direction control lever on the steering wheel column is moved from the forward position to the reverse position, the linkage moves forward/reverse selector valve (8) from the forward to the reverse position. Orifice (21) maintains oil pressure to 4-WD clutches when oil pressure drops during transmission directional clutch shifts. As the selector valve changes position it passes through the neutral setting. At this position the system pressure is open to reservoir, causing modulating relief valve (12) and load piston (10) to return to a neutral position. The spring behind the load piston forces the oil to drain by opening check valve (13). As oil drains, load piston (10) moves all the way to the right. Once the selector valve is in the reverse position, oil pressure is directed to reverse clutch assembly (2). The forward clutch is open to drain. Modulation operates similar in REVERSE as it does in FORWARD. See NEUTRAL to FORWARD for explanation.
Transmission Hydraulic System In Forward With Neutralizer Activated (Engine Running - Type 1) (1) Forward clutch assembly. (2) Reverse clutch assembly. (3) Input shaft assembly. (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer solenoid. (7) Flow control spool. (8) Forward/reverse selector valve. (9) Oil filter. (10) Load piston. (11) Oil pump. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (15) Inlet relief valve for torque converter. (16) Screen. (17) Oil cooler. (18) Oil reservoir. (19) Torque converter. (20) Orifice for torque converter bypass. (A) Pressure tap for reverse clutch. (B) Pressure tap for pump. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (E) Pressure tap for torque converter outlet. (F) Pressure tap for lubrication and cooling. Engine Running (Forward With Neutralizer Activated)
Transmission Hydraulic Control Valve (Type 2 And Type 3) (4) Transmission control valve. (5) Neutralizer valve. (6) Neutralizer valve. (7) Flow control spool. (8) Forward/reverse selector valve. (10) Load piston. (12) Relief valve. (13) Check valve for load piston. (14) Orifice for load piston. (A) Pressure tap for reverse clutch. (C) Pressure tap for forward clutch. (D) Pressure tap for torque converter inlet. (G) Pump oil. (H) Return oil. (J) Converter inlet oil. To activate neutralizer solenoid (6) the neutralizer button switch located on either the shift lever or loader control lever must be pushed in and held. When the neutralizer solenoid is energized the solenoid will move neutralizer valve (5) to the left. This shuts off supply oil and opens a drain passage for forward clutch oil and a drain passage for system pressure to proceed to the reservoir. The forward clutch instantly loses pressure thus putting the transmission in NEUTRAL. Load piston (10) and relief valve (12) return to their NEUTRAL position. Load piston check valve (13) allows oil to the right of the load piston to go to drain quickly. At this time relief valve (12) has a lower (initial setting) relief pressure for the transmission circuit. Orifice (21) maintains oil pressure to 4-WD clutches when oil pressure drops during neutralization for transmission speed shifts. The transmission will remain in NEUTRAL until the neutralizer button switch is deactivated (released).
When the neutralizer button is released, the neutralizer solenoid is de-energized. With the solenoid deenergized the neutralizer valve spring will return the neutralizer valve to the right, thus closing off both drain passages. Oil pressure is then allowed to fill the directional clutch and increase to maximum system pressure thus returning the transmission to the direction that was selected. Do not operate the engine at high idle speed with cold transmission oil. The cold oil may prevent the neutralizer valve from functioning properly and the machine could move.