Look at the design page for info on the plywood velomobile construction.

Thursday, 29 December 2011

Hydraulic drive

check valves allow pedaling and free wheeling
Why not choose a hydrostatic transmission for the velomobile?

When I see a drum brake I think: In the same volume a hydromotor fits with about the same mass. With that motor one could drive and brake the velomobile. While braking energy may stored in a nitrogen volume to be used for starting again. A small electric motor could easily be added to the system.

Hydrostatic transmissions are used when high torques, power and control are needed. The efficiency of these drives use to be smaller compared to gears or chains. But the efficiency can be improved a lot. Innas has developed machines with pump efficiencies up to 97%. I think a hydrostatic transmission developed for the velomobile may compete with the derailleur en planetary gear systems.

Imagine two pedal cranks that are swinging about 120ยบ. Each connected to a hydraulic cylinder. Both front wheels of the velomoble are fitted with a small hydro motor. The scheme shows the basic system. Questions left: How to make it a variable transmission? How to realize a rear driving option?


  1. hi Titus,

    A French company tryed to do somethink like that few year ago


  2. Thank you for your link. Compare the Cyclo pump with an Floating cup axial piston machine: The Cyclo has friction all over ! I doubt it will ever reach the high efficiency needed. How is your project going on ?

  3. Instead of a motor I was thinking that a velomobile with flywheel system could be fine. The problem with a velomobile seems to be reaching max speed, at least for traveling in a city for which it is common to have to slow down/stop. May that be possible to use some hydraulic transmission to the flywheel?
    My idea may sound crazy but tht would be great to be able to recover speed with a kind of a low tech like a flywheel...
    I wish I were a mecanical engeneer but I'm a physician !

  4. Physician should do I think. The idea is to compress a gas when decelerating and use the potential energy in the compressed gas to accelerate the velomobile again. This is a well proven concept. Hydraulic engineers call the gas volume an accumulator. In the accumulator oil and gas are separated to avoid gas dissolving into the oil. Nitrogen is used because normal air in contact with hydraulic oil may form explosive mixture.

    A flywheel is another interesting concept. Because of the high speed the combination with an electromagnetic drive is more apparent.

  5. Hi there. Nice blog. You have shared useful information. Keep up the good work! This blog is really interesting and gives good details. hydraulic cylinder manufacturer in Delhi, hydro cylinder supplier Delhi.