Safe & Reliable Screw-Driven Elevator | Stainless Steel Design with Emergency Stop Button

How a direct screw and nut drive actually works

Forget the marketing language for a moment. The machine has three parts that matter: a threaded steel screw, a nut that engages those threads, and a carriage that carries the car. When the nut turns it climbs the screw, and when it stops turning it stays where it is, because the thread angle is chosen so the load cannot push the nut back down on its own.

That last sentence is the whole safety argument, and it is worth reading twice. The car is not held up by a brake that has to release before the car can move; it is held up by the same threads that move it. A brake can wear, stick or be mis-adjusted, while a non-reversible thread has nothing to release. That is why screw drives turn up in private houses and small care properties, where a lift that strands somebody between floors is a serious event rather than an inconvenience.

What the screw drive changes about the building

Because nothing is suspended from a rope and nothing has to be pushed from below by a jack, the structural demands differ from both of the other drives. No traction machine sits on the roof, so no load is hung over the headroom, and there is no cylinder to bury. What the building does have to provide is a continuous vertical run wide enough for the guide rails, a structure that can carry the loaded car and react the drive torque, and a landing where the door frame can sit.

Where the screw drive sits between the other two drives

Most residential projects come down to three candidates, and they are not interchangeable. The table below is written to make the choice obvious rather than to flatter one column.

Read the first row again if you are comparing quotes: only one of these three keeps the car up without a brake or a valve holding it, and that is the one on this page.

Safety devices, and what each one is for

A screw-driven elevator is often bought on the strength of one sentence: the car cannot drop. That sentence is true of the mechanism, but it is not the whole safety story. An anti-drop screw elevator stops the car falling on its own; the devices around it stop people being caught, crushed or trapped, and stop the drive being overloaded until something gives.

The list below is what is on the machine and what job each item does. If you are comparing quotes, ask every supplier to tick the same items and you will find out who is selling a mechanism and who is selling a lift.

The device schedule

Work down the list and tick what your project needs. Every item is either on the machine as standard or is confirmed on the drawing before manufacture.

What this page does not claim

Approvals, test certificates and marks are project-level documents, and which of them your installation needs depends on the country, the building type, the rated load and whether the lift carries the public. This page therefore does not claim a certification, a standard number or a conformity mark for the machine; treat a page that does so without showing the paperwork with the same suspicion.

What you can do is ask for the current document set for your market before you order, and check that the certificate names the drive type and the load you are buying rather than the factory in general. Contact our engineers and we will send what applies to your project, and say plainly if something is not available.

Reasons a screw lift is refused

Most refusals are not about the drive; they are about the space around it. A stairwell void is not a shaft, because the landing doors need a solid wall beside them and the guide rails need something to be fixed to. The inner width quoted for a car is not the shaft width either, since the frame, the door track and the rail clearance come out of the same opening. The drive also applies a turning reaction into the structure, and that load path has to be designed rather than assumed.

Key specifications in one table

The figures below are the ones this model is quoted against. They are taken from this page's own specification table, including the two entries that are flagged in the next section because they differ from what screw drives usually publish. Switch between metric and imperial to read them in the units your drawings use.

Values are quoted from this page's specification table. Where a figure is marked “as listed”, the note below explains what to do before relying on it. ask our engineers for the drawing values that apply to your project.

How to read a screw-lift specification sheet

Two habits separate a specification you can build from a specification you merely like.

First, check that each figure names the condition it was measured under. A noise figure means nothing without the speed and distance it was taken at, and a load figure means nothing unless you know whether it is the rated load of the car or the capacity of the drive.

Second, check that the figures are consistent with the drive. Screw drives are a low-rise, low-speed, self-locking family by construction, so a sheet that pairs one with very long travel and a high speed is either describing a different machine or carrying a number that has not been updated. That is exactly what the next section is about.

A note on two entries in the specification table

Two figures on this model's specification table deserve a straight sentence rather than a sales spin, because you will design around them.

There is a second reason to care, and it is not about us. Specification tables get copied between products and between suppliers, and a figure that has drifted out of date can travel for years. If you are comparing several screw-lift suppliers, ask where their travel and speed figures were measured and on which model. The supplier who can answer is the one whose other numbers are worth trusting.

Power supply and what it decides

The specification table gives the supply as AC 220 V or 380 V, 50 Hz. Treating that as “either will do” is how projects lose a week. The two options suit different motor sizes and different buildings, and the choice is usually made by what is already at the wall.

What an electrician needs to know

Four figures have to be answered before the supply can be connected, and none of them can be read off a web page.

• The supply actually present at the point of connection — phases, voltage and frequency as measured, not as remembered.
• The route and length of the cable from the distribution board to the controller position.
• Where the controller cabinet will stand, and whether there is clear space in front of it.
• Whether the lift circuit will be on its own protective device, with the earthing arranged by the electrical designer.

Give us those four and the drive, the controller and the cable schedule come back as one package.

What the lift does when the power goes off

If the supply fails while the car is between landings, the drive stops turning and the thread holds the car where it is. Nothing has to release for the car to stay put, and nothing has to be powered for it to remain safe.

What the failure does not do by itself is bring the car to a landing. That is a deliberate operation by a competent person using the release provided for the purpose, and you should have that routine in writing at handover.

Doors, cabin and the parts you actually touch

Everything the mechanism does is invisible once the shaft is closed. What the household lives with is the entrance, the sill, the car interior and the sound, and those are the parts that get damaged first, so they are worth deciding deliberately rather than accepting whatever appears on the first drawing.

The specification table is explicit about two of them. A stainless steel screw elevator door is what this model uses, and the door opening height is 2,000–2,200 mm. The cabin size is a variable rather than a fixed figure, which is unusual in this price band and is why a screw lift can be fitted into a house that was never designed around one.

Tap to enlarge

Three questions to settle before the shaft is built

The door and the car are decided late but built early, which is how projects end up with a lift that works and an entrance nobody likes. Settle three things while the builder is still on site.

• Which way the door opens, and onto what.
• What crosses the sill: foot traffic, a wheelchair and a pallet truck are three different designs.
• Whether the car interior can be reached and refitted with the car parked at a landing.

How the installation runs, in six stages

A screw-driven lift has fewer site activities than a hydraulic or traction installation, because there is no jack to sink and no machine room to build. It has the same number of decisions. The sequence below is the order the work actually has to happen in, and the point in each stage where a missing figure costs a week.

1. Survey and approved drawings

   Measure the shaft or the space that will become one: clear width, clear depth, the floor-to-floor heights of every level, and the headroom above the highest landing. Photograph from the lowest floor upwards, including the ceiling. The drive is confirmed here against the load, the number of stops and the supply, and nothing is ordered before the general arrangement is agreed.

2. Preparation of the shaft and openings

   Floor openings are formed, shaft walls built or dressed, and the fixing points the guide rails and the drive are anchored to are provided. The load path for the loaded car and for the drive reaction is built here, and if the car will be loaded where it stops, that floor belongs to this stage.

3. Power, earthing and controller position

   The electrician brings the supply to the agreed place, installs the protective device, provides the earth and leaves the cable ready for the controller. Cabinet position is fixed here with clear access in front of it, because a controller reachable while the building is empty and blocked once the furniture arrives is a common and avoidable mistake.

4. Delivery and mechanical installation

   Screw, carriage, car, guide rails and door set arrive together and are installed as one assembly. The screw is set plumb and the rails aligned to it, because the nut travels on the screw and the car follows the rails: any error between the two shows up as noise and even wear.

5. Setting, testing and handover

   The controller is configured for the travel and the stops, then tested through the full cycle: every landing, the emergency stop, the overload, the door sensors and the interlock, with levelling checked at each landing rather than once. Handover is when the recovery routine is demonstrated and written down.

6. First service and the year ahead

   This first scheduled visit confirms that the nut, the thread, the guide shoes and the door gear are wearing evenly, and that nothing has settled since installation. The warranty runs for one year, and the parts that consume themselves in that year are the ones to watch. From then on the rhythm is a small number of checks done regularly.

What usually delays a screw-lift installation

Delays repeat across installations, and almost none of them are about the drive.

• The shaft arrives a different size from the drawing. Walls get built to the builder's convenient dimensions rather than the approved ones. Measure before the lift is packed, not after it lands.
• The supply is present but not sized. The circuit exists, but nobody has checked that it will carry the drive and protect it. This is the most common reason a commissioning visit ends early.
• Finishes and responsibilities are settled late. Floor thickness changes the sill height, and the sill is set when the doors are installed, so choose the finishes first. Agree in writing who does the builder's work and who does the electrical work, because the lift package covers the lift only.

None of these are reasons to avoid a screw lift. They are reasons to send the measurements early and to keep the drawing that everything else is measured against. Send site photographs before you commit and we will mark up what is still open.

Maintenance, spares and the one-year warranty

Maintenance on a screw-driven elevator is short, and short for a structural reason: there is no oil to change, no hydraulic pressure to hold and no rope to inspect. What there is instead is a nut running on a thread, guide shoes running on rails, and door gear that opens and closes every time somebody uses the lift. Those three are where the attention goes.

A maintenance rhythm that actually gets followed

Maintenance plans fail when they are ambitious: a short list that is genuinely carried out beats a long one that is postponed. For a residential screw lift, the rhythm that survives contact with a busy household looks like this.

• Monthly, by the owner: look at the landings and the car interior, listen for new noise, and check that nothing is stored in front of the door or in the headroom.
• Annually, by a technician: inspect the nut and thread, the guide shoes, the door gear and the interlock, test the emergency stop, the overload and the sensors, and read the controller's fault history.
• After any unusual event: if the lift has been overloaded, flooded or has stopped between landings, get it examined rather than simply re-set.

Questions to ask any screw-lift supplier about service

These questions separate a supplier who will still be useful in five years from one who was useful for a quotation. Write the answers into the order documents, because a service promise that exists only in a chat thread has a way of evaporating.

• Which part is designed to wear, and what is its expected replacement interval for your traffic?
• Can you have the part numbers for the consumables at handover, as individual items?
• Can a technician read the controller's fault history without special software?
• Who carries out the annual inspection in your country?
• What is excluded from the one-year warranty, and what is the procedure if a part fails within it?

Contact our engineers for the maintenance schedule for this model before you order.

Questions buyers ask before ordering

These are the questions that arrive by email most often, answered the way we would answer them on the phone. Where an answer depends on your project, it says so instead of guessing.

What to send for a quotation

A screw-driven elevator is priced against your building, not against a catalogue number, so a useful quotation needs a short list of facts rather than a long list of wishes. Send what you have and mark what you do not; the gaps become questions instead of assumptions.

Convert the units your drawings use

Drawings arrive in whichever units the site works in, and the quotation comes back in metric. Check the figures in both columns before you send them, so the enquiry and the reply are in the same language.

The printable safety and survey sheet

This is the same checklist the surveyor works through, put in a form you can carry to the site and write on. Print it, fill it in at the building, and send the pages with your enquiry. It answers most of the questions a quotation would otherwise raise.

Send the completed sheet with photographs and you will get an answer about your building rather than a generic price list. If a line cannot be filled in, say so and name what is missing: a marked gap is more useful than a guessed figure, and far cheaper than a lift that has to be altered after delivery.