Scissor Lift Table with Hydraulic Cylinder and Foot Pedal

Workshops often need to raise heavy assemblies — engines, gearboxes, machine sub-frames — to a comfortable working height, and doing it with brute force or stacked blocks is unsafe and imprecise. A scissor lift table solves this with a classic mechanism: crossed steel arms pivoted at the centre convert a short push from a hydraulic cylinder into a large vertical lift, giving a big mechanical advantage from a simple, robust linkage. This project builds that machine in the college fabrication shop: mild-steel flat-bar scissor arms on pivot pins, welded base and top frames, a welded hydraulic cylinder fed by a foot-pedal pump through a high-pressure hose, a 600×900 mm chequered platform, caster wheels with brakes, a mechanical safety prop bar and a hand-operated needle valve for controlled lowering. The design load is 200 kg — stated as a design target from calculation, with a buyer-run proof-load procedure included. Being pure human-powered hydraulics, the build demonstrates fluid power, mechanism design and fabrication in one project, with no electronics to hide behind.

1. The operator rolls the table into position on a flat, level, hard floor and locks all four caster brakes.
2. The load — centred on the platform and within the 200 kg design load — is placed on the 600×900 mm chequered plate.
3. The operator pumps the foot-pedal treadle; each stroke pushes a small volume of jack oil through the high-pressure hose into the welded hydraulic cylinder.
4. Oil pressure extends the piston rod, which pushes against the scissor linkage; the flat-bar arms rotate about their pivot pins, the X closes, and the top frame and platform rise a few millimetres per stroke.
5. At the working height the operator swings the mechanical safety prop bar into its notch, so the raised load is carried by the steel bar and not by oil pressure.
6. To lower, the operator first releases the prop bar, then cracks open the needle valve by hand; oil meters back to the reservoir at a controlled rate and the platform descends smoothly.
7. Before first real use, the student runs the documented proof-load procedure: the platform is loaded in steps up to the 200 kg design target while lift height, drift and weld behaviour are observed and recorded.
8. Air in the circuit is bled at the cylinder port during commissioning so the pedal strokes stay firm and the motion stays predictable.

Design calculation (shown as calculation, not a measured claim): Design load 200 kg → weight force 200 × 9.81 = 1962 N. Applying a scissor-linkage force factor of 1.5 (design assumption), the cylinder must push approximately 2943 N. Selected cylinder bore 40 mm → piston area π/4 × 40² = 1256.6 mm². Required pressure = 2943 ÷ 1256.6 ≈ 2.34 N/mm² ≈ 23.4 bar. The relief valve is therefore set at approximately 30 bar (design setting). Cylinder stroke 200 mm maps to approximately 450 mm of platform travel through the scissor geometry (design target). These figures are the design basis the student verifies with the proof-load procedure; they are not claimed as tested results.

Tech stack:

• Mild steel fabrication (flat bar, square tube, plate)
• Welded hydraulic cylinder (40 mm bore)
• Foot-pedal hydraulic pump with reservoir
• High-pressure hose · fittings
• Needle valve lowering control
• Chequered steel platform plate
• Caster wheels with brakes
• Mechanical safety prop bar

• [Foot-pedal hydraulic pump] A treadle-style foot pump with an integral oil reservoir builds system pressure by hand-pumping, so the table lifts loads with no electricity, motor or external power source — ideal for workshops without power points.
• [Single-stage scissor linkage] Two pairs of mild-steel flat-bar arms cross in an X and rotate about central pivot pins, converting the cylinder's short stroke into approximately 450 mm of platform travel with fine, controlled motion.
• [Welded hydraulic cylinder] A black welded hydraulic cylinder with a chrome piston rod is pinned between the base frame and the scissor linkage; the piston force is sized from the design calculation, not guessed.
• [Needle-valve lowering control] A hand-operated needle valve meters oil back to the reservoir, so the platform descends slowly and predictably instead of dropping.
• [Mechanical safety prop bar] Once raised, a steel prop bar swings into a support notch and carries the load mechanically — the table never relies on trapped oil pressure alone while anyone works near it.
• [Mobile caster base with brakes] Four caster wheels make the table easy to roll into position; brakes on the casters lock it solid before any lifting begins.
• [Chequered anti-slip platform] A 600×900 mm diamond-pattern steel plate gives the load a non-slip working surface and resists the dents and scratches of real workshop use.
• [Design-calculation documentation] The full design calculation — load force, cylinder bore from F = P·A, scissor linkage factor, relief-valve setting, stroke-versus-lift geometry — is documented step by step for the report and the viva.

• Working prototype: fabricated and assembled scissor lift table, commissioned and bled
• Design calculation sheet (load force, cylinder bore, linkage factor, relief setting, stroke-versus-lift geometry)
• Fabrication drawings / general-arrangement sketch with member sizes
• Bill of materials with sourcing notes for the cylinder, pump, hose and fittings
• Operating and maintenance procedure (including the air-bleeding step and the proof-load procedure)
• Project report PDF (background, mechanism theory, hydraulics basics, design calculations, fabrication method, results of the proof-load run)
• PPT presentation for final review
• Viva Q&A preparation document (scissor mechanism, Pascal's law, cylinder sizing, safety)