Controllable load apparatus
The invention relates to a controllable load apparatus for use in machines for resistive exercise training of the human body. The apparatus comprises a pneumatic cylinder ( 10 ) having a piston ( 12 ) acting on a fluid and a piston rod ( 14 ), the piston/cylinder unit ( 10, 12 ) being operated on by a person undergoing training. A pressure accumulator ( 20 ) is connected to, and pressurizes the piston/cylinder unit ( 10, 12 ) at a predetermined pressure during exercise via a pneumatic control circuit ( 42 ). Once a predetermined pressure threshold is reached, a valve means operates to prevent further fluid being available for charging the accumulator ( 20 ).
1. A controllable load apparatus for use in resistive exercise training, the apparatus comprising a fluid piston/cylinder unit which, in use, is operated on by a person undergoing training, a pressure accumulator connected to pressurise the piston/cylinder unit at a predetermined pressure during exercise, and pressure setting means for setting said predetermined pressure in the pressure accumulator; and in which the piston/cylinder unit is in communication with the accumulator through a pneumatic control circuit which in an initial mode permits operation of the piston/cylinder unit by a user to initially pressurise the accumulator with ambient air to said predetermined pressure, and in a working mode connects the same piston/cylinder unit directly to the accumulator for training.
2. Apparatus according to claim 1 , wherein the pressure setting means comprises a changeover valve within the pneumatic control circuit which operates at a predetermined pressure to prevent further fluid being available for charging the accumulator.
3. Apparatus according to claim 2 , in which the changeover valve is an electrically operated valve which may be controlled by an electronic circuit or program device.
4. Apparatus according to claim 1 , in which the working fluid is air.
5. Apparatus according to claim 1 , in which the cylinder is fixed and the piston is moved by the user.
6. Apparatus according to claim 1 , in which the piston is a plain piston.
7. Apparatus according to claim 1 , in which the piston is provided with a valve or restrictor such that the piston/cylinder unit acts in the manner of a gas strut to provide a substantially constant force throughout the stroke.
8. Apparatus according to claim 1 , in which said piston/cylinder unit comprises twin pistons which are coupled together for normal use and which are decoupled to provide a reduced area for initially pressurising the accumulator.