KEVOS® MAKEOS · Hydraulics
Hydraulic Hand Jack Check (Handle Leverage, Pump Pressure, Lifting Force, Strokes to Lift)
For a hand-pumped hydraulic jack or press, what pressure does the handle effort make, can it lift the load, and how many pump strokes does the lift take?
Check of a hand-operated hydraulic jack or press: the force on the pump plunger from the handle effort and lever arms (as the lever force tool), the pressure from the plunger area, the lifting force of the ram with an efficiency, the effort needed for the rated load, and the number of pump strokes to raise the ram by the lift height from the ratio of displaced volumes, against the load, the system pressure rating and a limit on strokes.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Handle effort | N | Force the operator applies at the end of the handle. |
| Handle length (pivot to hand) | mm | Distance from the handle pivot to the hand position. |
| Pivot to plunger | mm | Distance from the handle pivot to the plunger pin. |
| Pump plunger diameter | mm | Diameter of the pump plunger. |
| Ram diameter | mm | Diameter of the lifting ram. |
| Overall efficiency | % | Overall efficiency of the pump and ram (seal friction and leakage). |
| Duty | ||
| Load to lift | N | Load the jack must lift. |
| Pressure rating of the jack | MPa | Highest pressure the jack is rated for (relief valve setting). |
| Lift height | mm | Height the ram must rise. |
| Plunger stroke | mm | Stroke of the pump plunger per handle stroke. |
| Most strokes accepted | strokes | Most handle strokes acceptable for the lift. |
Method and formulas
- Plunger force = effort × handle length ÷ pivot distance (as the lever force tool).
- Pressure p = plunger force ÷ (π d_p² ÷ 4); lifting force = p × π D_r² ÷ 4 × efficiency.
- Pressure for the load = W ÷ (π D_r² ÷ 4 × η); strokes = D_r² h ÷ (d_p² s_p), rounded up.
- Example: 33.157 MPa lifts 37.5 kN; 84 strokes raise it 150 mm.
Limitations
- Static balance; seal friction varies with pressure and is taken in the efficiency.
- Leakage past the check valves adds strokes.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a bottle jack or workshop press
- Choose plunger and ram sizes for a hand pump
- Find the handle effort for a given load
Who it is for
- Design engineers
- Maintenance fitters
- Engineering students
What you get
- Plunger force and pressure
- Lifting force and effort for the load
- Pressure and strokes for the lift
Interpreting the result
- The force multiplication is the lever ratio times the area ratio; the strokes needed grow with the same area ratio.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 167–168, 3024–3027. Topic reference; no source tables or recommended settings are reproduced.
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