Wobble plate 2 has a spherical thrust bearing with its centre at point 0. Plate 2 rolls around conical surface a. Pistons 3 end in cones b which slide along wobble plate 2. By means of the wobble plate, rotation of shaft 1 is converted into reciprocation of pistons 3. The pistons are loaded by springs 4 to keep them in contact with wobble plate 2 .
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