This service manual gives the disassembly and reassembly procedures for torque converters and transmissions used in Tadano rough terrain cranes. The models of the units covered by this manual and the applicable parts of the manual are listed in the table below. Check the models of your converter and transmission by referring to the nameplates of the units, and read the applicable part. Use this manual in conjunction with the relevant parts catalog, crane service manual and other reference materials and make proper preparations.
This torque converter is a 3-element, 1-state, 2-phase unit composed of an impeller vane wheel, a turbine vane wheel, and a stator vane wheel.
Tadano Crane R561-Z101 Repair Manual
The converter fluid flows through a path composed of an impeller vane wheel , a turbine vane wheel and a stator vane wheel. The periphery of the impeller wheel is bolted to the cover wheel, and the latter is fixed to the engine flywheel via the input plate. The bore of the impeller vane wheel is supported by a ball bearing, which is mounted on the freewheel inner race bolted to the stator holder. The engine drive motion is directly transmitted to the impeller wheel and then, through the fluid, to the turbine wheel assembly.
The turbine wheel ass'y is splined to the turbine shaft, on the other end of which the drive gear is splined. The drive gear is in mesh with the driven gear which is splined to the output shaft. The engine drive motion is transmitted to the output flange through the above route.
The stator wheel is supported by the converter housing via the freewheel cam, the freewheel rollers, the freewheel inner race, and the stator holder. The stator wheel serves to raise the turbine torque above the input torque by adding the reaction torque, generated by the working fluid returning from theturbine wheel ass'y to the impeller wheel, to the turbine torque. At high speeds, the stator wheel becomes idle and loses torqueconverting function, in order to maintain the transmission efficiency at a high level.
TORQUE CONVERTER & TRANSMISSION
Fluid clutches, transmitting rotational power by means of fluid, are classified into two major categories; the fluid coupling, and the torque converter. Their main components are shown below in Fig. 1.
Fluid coupling are fluid clutches consisting only of pumps (impellers) and turbines , and they convey rotational motion just as a wind wheel installed face to face with an electric fan is driven by the fan. When the pump (impeller) is driven by an engine, the fluid (oil) starts to rotate around the shaft, and is driven outward by the centrifugal force. With the pump (impeller) provided with radial vanes , oil flows out from the periphery of the vane wheel of the impeller, and flows into the periphery area of the turbine wheel which is installed face to face with the imperller From the periphery area of the turbine, the oil flows towards the center area along the turbine blades, exerting rotational force to the blades, and eventurally, returns to the pump (impeller) through the center area. See Fig. 2.
Since oil, the transmission medium, must be continuously used within the sealed space in a fluid coupling, the transmission efficiency is low and large input torque is required to drive the turbine when the pump (impeller) and the turbine run at a large speed difference, that is, when starting the turbine from standstill, and when climbing an uphill. With a torque converter, a staror wheel is placed between the turbine outlet and the pump (impeller) inlet, to improve the transmission efficiency under heavy loads.
In the fluid coupling, the oil return flow from the turbine to the pump (impeller) is in the direction to detard the pump rotation at the impeller vane inlet, but in a torque converter, the return oil flow is turned around by the stator wheel into the direction of pushing the impeller blades foward, resulting in the improvement of efficiency under heavy loads, and even results in the transmission of larger torque than the input torque to the turbine.
The stator is so designed that it can be either left free to be directed by the flow of oil discharged from the turbine outlet, or fixed to guide the return oil into the direction to improve the converter effciency. When the load is small, such as in cruising at high speeds, the speeds of the impeller and the turbine are not much different. As this condition is approached, the discharge oil from the turbine outlet changes flow direction towards the rotating direction, and eventually, it starts to hit the rear side of the stator blades.
When this happens, the stator impedes the oil flow, and the efficiency of the converter is reduced. To prevent this, the stators of torque converters are provided with a one-way clutch allowing the stators to freely run to follow the oil flow, when the stator blades are pushed from the rear side. This means that the stator is locked in one direction to amplify toque, and in the oppsite direction, it moves free to make the converter operate as a fluid coupling under light load conditions.
Pump drive system
The converter housing is provided with three power takeouts; the main pump drive PTO clutch, the steering pump drive, and the charging pump drive, and they are driven by the drive gear bolted to the impeller wheel.
Tadano Crane R561-Z101 Service Manual
The torque converter oil is pumped by the charging pump through the strainer (80-mesh) from the transmission oil tank, adjusted in pressure by the PTO clutch oil pressure regulator valve mounted on the transmission , and is sent to the PTO clutch inlet port.
The oil flowing into the torque converter flows through the space between the turbine shaft and the freewheel inner race, and flows into the converter circuit from the left side of the stator wheel. The oil flows out of the torque converter from the right side of the stator wheel, flows through the groove on the freewheel inner race and the stator holder, and flows out of the converter housing. The oil flowing out of the torque converter is cooled in the oil cooler, lubricates parts of the transmission, and returns to the tank.
Tadano Crane R561-Z101 Repair Manual For Free