A telescopic hydraulic cylinder provides long extension from a comparatively short collapsed package by using nested stages. This calculator compares ideal static pressures for two entered effective stage diameters; it is not an elevator design, capacity or safety tool.
Telescopic Hydraulic Elevator Interactive Calculator
Enter supported mass, two effective loaded diameters and a comparison pressure limit. The model applies P = F/A with F = mg and A = pi d squared over four.
Equation Used
- Each entered diameter represents the effective loaded circular area for that stage.
- The same entered mass acts vertically on each stage and g = 9.81 m/s squared.
- Opposing pressure, friction, seal drag, acceleration, side load and structure are omitted.
- The entered pressure limit is a comparison value only; ratings, codes, factors of safety and control behavior are omitted.
Telescopic-cylinder Principle
Parker's cylinder guide describes telescopic cylinders as a way to obtain long stroke from a relatively short collapsed length. It also explains that different effective stage areas produce different force and speed behavior, and that the smallest stage commonly limits force capacity.
The animation is conceptual and shows nested members extending in sequence. It does not reproduce a specific elevator cylinder, stage-sequencing circuit or installation.
What This Explanatory Calculator Does
The calculator treats each entered diameter as the effective loaded diameter of a circular hydraulic area. It divides the entered supported weight by that area to obtain an ideal static pressure for each state.
It does not select a cylinder, predict actual sequence or motion, size a pump or relief valve, establish elevator capacity, or address applicable codes and inspection.
Ideal Static Pressure Comparison
With the same ideal force on both stages, PB/PA = (dA/dB)². The signed comparison margin is the entered pressure limit minus PB. NIST defines pressure as force per unit area; Parker notes that actual telescopic-cylinder calculations require the correct effective area established by seal boundaries.
Worked Ideal Comparison
For 5,000 kg supported mass, effective diameters 134 mm and 60 mm, and an entered comparison limit of 200 bar, the ideal pressures are about 34.8 bar and 173.5 bar. Their ratio is about 5.0, and the signed comparison margin is about +26.5 bar.
This does not include car mass breakdown, friction, acceleration, back pressure or any required design allowance.
Model Boundary
- Calculated: ideal weight, circular areas, two static pressures, their ratio and a signed arithmetic comparison to an entered limit.
- Manufacturer guidance: effective areas differ by stage and depend on construction and seal boundaries.
- Not calculated: stage sequence, stroke, speed, flow, cycle time, opposing pressure, friction, seal drag, acceleration, side load, buckling, overlap, mounting, structure, controls, valves, pressure rating, factor of safety, elevator capacity, ride behavior, codes, inspection or maintenance.
Frequently Asked Questions
Why does the smaller entered diameter require more pressure?
The same ideal force divided by a smaller area gives a larger pressure.
Are the entered diameters outside diameters?
Not necessarily. They must represent the effective loaded areas; actual construction and seal boundaries determine those areas.
Does a positive margin prove the stage will move?
No. It is only an arithmetic comparison and omits friction, back pressure, dynamics and controls.
Does the tool predict extension order?
No. The animation is illustrative; real sequencing depends on the cylinder and circuit.
Can this set a relief valve?
No. Ratings, design allowances, codes and valve behavior are outside the model.
Can this size an elevator?
No. Elevator engineering requires complete loads, geometry, components, controls, applicable codes and qualified review.
References
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