Hydrowinch LLC is the first glider winch manufacturer to use hydrostatic power. For several decades the glider world has been using torque converters (automatic transmissions) to drive their winches. While developing our winch concept we didn't just follow the masses but asked ourselves the question: What is the best solution to achieve our goals to provide:

• Maximum safety, ease of use

• Reliability, high availability rate

• Economics, low operational and maintenance costs

• Performance, a good alternative for towing

Efficiency

Automatic transmissions are very inefficient for the heavy pulling required of a glider winch. With the conversion from steel cables to synthetic ropes the maximum release height is no longer limited by the cable weight. Launching to greater heights creates a problem for the torque converter. The high level of slippage overwhelms the converter's ability to dissipate heat, resulting in a rapid degradation of the oil quality and damage to the seals that retain oil inside the converter.

Hydrostatic drives are very efficient and consume only the power that is necessary. During the launch the engine runs constantly at it most efficient speed. A hydraulic cooler with thermostat regulates the oil temperature to maintain a constant oil quality for many years, even in harsh conditions.

Rigidity

Hydrostatic drives are fitted with safety valves that protect the system against overloads. Overloads typically occur by a glider entering a thermal or due to mechanical failures. Overloading torque converters may result in stator clutch seizure or blade deformation. A converter with a seized stator clutch exhibits very poor efficiency and fuel consumption. Converter overheating under such conditions will usually occur if continued operation is attempted.  

Controllability

The key factor where hydrostatic drives outperform torque converters is the ability to control the output speed and torque. Hydrostatic drives own the natural talent of generating a constant torque or pull force independent from the input or output speed.

Provided with the appropriate pull force the pilot is able to control the airspeed himself. To reduce airspeed he or she gently pulls the stick. To increase airspeed the pilot gently eases forward on the stick. In contrary to traditional winches with torque converters, the glider gains extra height in a thermal.

Safety

The increasing weight of gliders demands more power from the winch. New glass ships with water ballast tanks require 300 hp and the end of this trend line is still not in sight. Now, imagine yourself sitting in a 500 lbs glider being launched by a manually operated 300 hp winch. An uncontrolled acceleration can push the pilot in the seat, not able to reach the controls or release. Or the weak link fails close to the ground, just after the glider auto-rotated to a steep climb angle due the acceleration burst. Hydrostatic drives can accelerate independently from the glider weight, launching every type of glider in a similar way.