TL;DR: A tail lift is a suspended platform, so the cylinder is not lifting a dead weight straight up — it pushes through a linkage that multiplies the load several times. Size the bore from that lever-arm force at your working pressure, size the power unit backward from the cylinder's flow, and fit a load-holding valve so the platform cannot creep down on its own. Most 1500 kg tail lifts land around a 70 mm bore at 140–160 bar and a 2.2–2.8 kW motor at 12V or 24V.
A refrigerated van I worked on kept tripping its thermal cutout on the ramp. The driver blamed the motor, but the motor was fine — the fitter had specified a power unit at the load's dead weight and ignored the linkage. The cylinder was running at the ragged edge of its relief valve just to hold the platform up. Swap the sizing order and the whole job becomes simple.
Why the load is not the load
A tail lift does not lift 1500 kg in a straight line. The platform sits at the end of a parallel linkage, and the cylinder acts close to the hinge. The lever-arm ratio is what bites: a load centred 445 mm from the pivot, pushed by a cylinder only 89 mm out, needs roughly five times the load at the cylinder rod.
That is why a published "1500 kg" figure tells you almost nothing about the cylinder until you know the geometry. Two different lift designs rated for the same platform can want wildly different bores.
Bore from force, not from the nameplate
Start with the worst-case force, which is the start of the lift. Work out the rod force through the linkage, then divide by the piston area to get your working pressure. Round the bore up to the next standard size — never down — and re-check the real force at that bore.
A worked example from a cantilever tailboard design is worth keeping on hand: a 1.5 t platform at a 445 mm load arm, driven by a cylinder at an 89 mm moment arm, calls for about 37.5 kN per cylinder once you halve for the two lift cylinders. At 14 MPa that lands on a 70 mm bore with a 30 mm rod and a 360 mm stroke.
| Step | What to compute | Rule of thumb |
|---|---|---|
| 1. Force | Rod force = platform load × lever-arm ratio | Check the start of lift, it is the worst case |
| 2. Pressure | Working pressure = force ÷ piston area | Size on working pressure, not relief setting |
| 3. Bore | D = √(4F ÷ πp) | Round up to the next standard bore |
| 4. Flow | Q = piston area × lift speed | Sets the pump displacement |
| 5. Motor | kW = (pressure × flow) ÷ 600 ÷ η | Add 10–20% margin |
| 6. Reservoir | 3–5 × pump flow per minute | Enough to shed heat and settle air |
Sizing the power unit backward
Power units get sized the wrong way all the time, because people start at the motor. You start at the cylinder. Take the piston area, multiply by the lift speed you actually need, and that is your flow. Then pressure times flow gives hydraulic power, and you divide by pump and motor efficiency to land on the motor rating.
A 1500 kg tail lift on a 12V or 24V circuit typically runs a 2.2–2.8 kW motor at 160–180 bar working pressure. The reservoir should hold three to five times the pump's flow per minute, both to settle air and to keep oil temperature down on a busy delivery route. Undersize the tank and you trade a cheaper build for a cooked seal six months later.
The valve that keeps the platform up
A tail lift is a suspended load, which is the one situation where a plain directional valve is not enough. Shift the spool to neutral and a load-holding valve or pilot-operated check must hold the platform exactly where it stopped. Skip it and the platform creeps down under its own weight, which is a safety problem as much as a nuisance.
If a lift starts to creep, check the holding valve first, then the piston seal. A steady slow descent under a static load is one of those two, and the valve is the cheaper fix.
Keeping two cylinders in step
Nearly every tail lift runs a pair of lift cylinders, and the two sides are rarely loaded evenly. A pallet parked to one side makes one cylinder want to extend faster than the other, and a racked platform bends linkages and smears rod chrome. A flow divider or a synchronizing circuit keeps both sides level.
This is cheap insurance. I would rather see a flow divider on a modest platform than a beefed-up cylinder on a racking one.
Matching a replacement to the chassis
When a tail lift cylinder is beyond a reseal, the replacement has to match the closed length, stroke, bore, end fittings and the mounting, because the whole thing tucks under the chassis when stowed. Get the closed length wrong and the platform will not fold flat against the tail.
Send us the old unit or the platform drawing and we reverse the stack — bore, rod, stroke and pin centres — and confirm a drop-in build against your circuit pressure. The custom hydraulic cylinder line covers the lift and tilt cylinders on both cantilever and tuck-under tail lifts.
Built and tested at HCIC
HCIC has made hydraulic cylinders and complete systems since 1998, from three plants and one R&D centre with 20+ engineers and 250+ staff. We produce 210,000 cylinders a year, 95% exported, to ISO 6020, ISO 6022 and ISO 10100. Every cylinder is pressure-tested before it ships — 3000 PSI proof on the lift range — with an 18-month warranty and a full maintenance kit included.
MOQ is one sample, and a quote comes back within 48 hours. Where a tail lift wants a compact motor-and-pump package, our hydraulic power units pair with the cylinder to keep the platform metered and level. For a tipping body that lifts through a telescopic hoist instead, see the dump trailer telescopic cylinder note.
Frequently asked questions
What bore cylinder does a 1500 kg tail lift need?
It depends on the lever-arm geometry and the working pressure, not the load alone. A tail lift lifts through a linkage, so the cylinder force is the platform load multiplied by the lever-arm ratio. At 140–160 bar, a 70 mm bore single-acting cylinder is a common fit for a 1500 kg platform on a 600 mm load centre; at lower pressure the bore grows. Send the platform drawing and we confirm the bore against your circuit pressure.
How do I size the power unit for a tail lift?
Start at the cylinder: flow Q = piston area × lift speed sets the pump, and motor power = pressure × flow / 600 (bar, L/min) divided by pump and motor efficiency. A 1500 kg tail lift typically runs a 2.2–2.8 kW motor at 12V or 24V and 160–180 bar working pressure, with a reservoir of three to five times the pump flow per minute.
Why does my tail lift creep down with the platform raised?
A load-holding valve or pilot check that is leaking, or internal bypass across a worn piston seal. The platform is a suspended load, so it must not rely on the directional valve to hold it. Check the holding valve first, then the seal; a steady, slow descent under a static load points to one of these two.
Do tail lifts need a flow divider between two cylinders?
Yes. Most tail lifts use two lift cylinders, and unequal loading makes one cylinder want to outrun the other. A flow divider or a synchronizing circuit keeps the two sides level so the platform does not rack and bind. It is cheap insurance against a bent linkage.