| 摘要 |
A short stroke hydraulic jack for lifting heavy loads. The jack comprises a piston and an open-ended cylinder of substantially equal length, which length is much greater than the length of the stroke of sad piston but much shorter than the respective diameter of the piston and cylinder. The piston is provided on one side with a load-bearing surface and on the other side with axially spaced concentric work surfaces and a centrally disposed shank. The cylinder has an end wall having a central opening therein for receiving said shank and axially spaced surfaces mating with the work surfaces of said piston whereby vertical surface-to-surface contact between the piston and cylinder is maintained in two radially spaced annular areas throughout the length of the stroke of the piston.
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