Details of Hondamatic mechanism

An ordinary hydraulic transmission for industrial machinery is not appropriate for motor vehicles from the viewpoint of transmission efficiency. In Hondamatic, the efficiency is enhanced by splitting the input power into hydraulic and mechanical components. Especially, to prevent leakage of high pressure fluid, which directly affects transmission efficiency, the unique distributor valve is employed. The automatic mode for infinitely variable automatic control of reduction ratio and the ESP mode allowing rider’s choice from 5 speeds are provided, and allow changes of reduction ratio without any shifting shock.
Infinitely-variable reduction ratio by means of variable-angle swash plate
The reduction ratio of Hondamatic depends on the pump-to-motor volume ratio. The angle of pump swash plate driven by engine power is constant all the time, and the seven hydraulic pump pistons produce a hydraulic pressure depending on engine power output. The electronically-controlled DC motor changes the angle of the motor-side swash plate via the gears and the ball thread, thus changing the motor cylinder volume without a step, which changes the reduction ratio continuously. Because of the above-mentioned working principles, the reduction ratio becomes maximum when the motor-side swash plate angle is at the maximum, and when the angle is minimum (vertical to the axis), there is no reciprocation of motor-side pistons, which causes a direct coupling with a theoretical reduction ratio of 1:1.
Pistons for hydraulic pump/motor and dimple plate
The dimple plates having spherical dimples corresponding 1 to 1 to the pistons are located between the hydraulic pump side and hydraulic motor side pistons and the swash plate. The dimple plate relieves stresses in the contact area and improves durability.

Distributor valve

The shifting of the high pressure fluid passage and the low pressure fluid passage in the piston chamber and the cylinder in each the pump and the motor is performed by the spool-type distributor valve paired with the piston and laid radial. The distributor valve is driven by the eccentric ring synchronized with the swash plate, and synchronized with the movement of each piston. The eccentric ring off-centered from the rotation center of the cylinder spins, the distributor valve repeats radial reciprocation against the cylinder, and shifts the high pressure fluid passage and the low pressure fluid passage in accordance with each out-going and in-coming strokes of the piston.

Distributor valve


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