VRP – Variable Ravigneaux Planet Functional description
VRP (Variable Ravigneaux Planet)
The VRP continuously variable transmission is based on the principle of a mechanical-hydrostatic power split using a special Ravigneaux planetary gear set. The gearbox has 3 superimposed ranges for forward and reverse travel. The individual superimposition ranges are switched via multi-plate clutches at synchronous speeds. A forward and reverse gear stage are arranged on the output side of the superimposed gearbox, which are engaged via jaw clutches. Permanent power flow is ensured over the entire speed range, even when switching from forward to reverse and vice versa.
The core element:
- The specially developed Ravigneaux planetary gear set enables optimum superimposition of the mechanical and hydrostatic power train.
Significant advantages:
- Very good efficiency in the main operating ranges
- Permanent torque flow between motor and drive wheels.
- The motor is operated in the optimum power range.
- Full tractive power even at low engine speeds.
- Switching from forward to reverse via a claw clutch enables uninterrupted gear changes
- No range switching in the lower speed range => no discontinuities in the power transmission
Maximum ride comfort and safe operation:
- Smooth, uninterrupted start-up
- Continuous flow of force during acceleration or deceleration
- Fully automated drive train
- Cruise control is integrated
- No stalling of the engine
- Full utilization of engine braking power during deceleration through targeted adaptation of the gear ratio
The patented VRP transmission system is based on the principle of hydrostatic-mechanical power splitting and is designed for high drive power. The transmission contains 3 power-split transmission stages each for forward and reverse travel. The drive ranges are switched by means of a multi-plate clutch without interrupting the tractive force at synchronization points.
The core element of the transmission is a Ravigneaux planetary gear set, in which the mechanically transmitted power and the variator power are superimposed. The drive power is transmitted purely mechanically in the middle of each driving range, which means that the best efficiency levels are achieved at these operating points.
Jaw clutches are installed at the gearbox output to switch from forward to reverse. These jaw clutches also enable uninterrupted gear changes and optimum efficiency even at very high speeds.
Starting from a controlled standstill is achieved by continuously adjusting the speed of the hydraulic motor. In tractors, the full drive power is transmitted purely mechanically at a speed of approx. 8 km/h. Optimum coordination with the best operating points of the combustion engine enables the best vehicle performance to be achieved in the speed range from approx. 5 to 12 km/h with minimum fuel consumption.
Switching from the first to the second power split range takes place at speeds of around 15 km/h. This means that no range shifts are required for heavy haulage operations. This feature also ensures optimum functionality when using the VTP transmission system in wheel loaders or similar applications, as high forces can be applied continuously (e.g. when cutting into piles).
Contact
Location
Gewerbepark 6
4493 Wolfern | Austria