Compact Screw-Driven Home Elevator | 400 kg, 50 ft

01 · Fit

Is this the right lift for the house?

A compact screw-driven elevator makes sense when the project has a narrow shaft, a long but finite travel, and a power supply that can support a single-phase drive. It is a poor fit when the building needs to move more than 400 kg, when the travel exceeds 50 ft, or when the site cannot provide the structural and electrical conditions the final design requires.

The decision is easier if you separate three questions: what the lift must carry, how far it must travel, and what the building can accept. The answers point to a model, a shaft layout, and a set of site works. They should be settled before anyone orders equipment.

When this model is the wrong choice

• Travel above 50 ft. The page limit is 50 ft (15.24 m). A taller run needs a different model or a different layout, not a longer rail cut on site.
• Rated load above 400 kg. If the actual load case includes heavy equipment, a large wheelchair, or several passengers, move to a higher-capacity model and check the car size as well as the number.
• High traffic or frequent goods handling. A 0.15 m/s residential lift is not a passenger elevator for an office, a shop, or a busy rental property.
• No single-phase supply. The published supply is 220 V, 50 Hz, single phase. A three-phase-only site needs an electrical solution confirmed by the supplier and the local electrician.
• No space for the car, door, and structure. “Compact” is relative. The car, door operator, guide rails, and landing sills still consume space; the approval drawing decides whether they fit.

What “400 kg” actually covers

400 kg is the rated load on this page, not a target to fill to the last kilogram. The useful load is the passenger or goods weight plus anything carried into the car, and it has to be read together with the car floor area and the door opening. For a private house, the practical question is “what is the heaviest realistic trip?” If the answer includes a mobility scooter, a bulky wheelchair, or building materials, write that load down and check it against 400 kg before selecting the model.

“Compact” describes the package relative to the travel and load, not a promise that it will fit any stairwell. Ask for a plan view with the car, door, rails, drive column, and maintenance clearances. If the drawing does not show those items, the compact claim cannot be checked.

02 · Drive and anti-drop

How a screw drive holds a car, and what “anti-drop” should mean

A screw-driven lift turns a rotating screw column. A nut fixed to the car travels up and down that column. Because the nut is captive on the screw, the car cannot simply fall free while the nut and screw remain engaged. That is the mechanical basis for the “anti-sudden-drop” language used on this page.

The holding force depends on the thread form, the nut material, the lubrication, the load distribution, and the condition of the nut. A screw drive is not a licence to skip a holding brake, a secondary load path if fitted, overspeed protection, or a periodic inspection.

Self-locking is a property, not a complete safety system

A screw thread can be self-locking when its lead angle is low enough that friction prevents the load from driving the screw backwards. That is useful, but it is not the same as a certified safety device. The holding brake, a secondary load path if fitted, the overspeed detection, and the door interlocks each cover a different failure mode. A supplier who says “it cannot fall” without explaining those layers is giving you a slogan, not an engineering answer.

Ask for the load path in writing: which component carries the car, what the secondary nut contacts, and how the assembly is inspected. If the answer is only a brochure phrase, keep asking.

In practice, the screw drive removes rope traction from the load path. It does not remove the holding brake, a secondary load path if fitted, the door interlocks, the landing detection, or the need to inspect the nut and keep the screw clean. Those items remain part of the safety case and the maintenance plan.

How to test the anti-drop claim

You cannot prove a safety function by watching a car sit still. Ask for a test procedure and a record. A useful sequence covers the brake, any secondary load path, the overspeed device, and the door circuit separately. Load the car to its rated load for the brake test, and repeat the test after installation, not just at the factory.

1. Holding brake test. Stop the car at a landing with rated load, remove drive power, and confirm the car holds without visible creep.
2. Secondary load path check. Ask whether a safety nut is fitted. If it is, confirm installation, gap, and the commissioning record.
3. Overspeed test. Use the manufacturer’s test method; do not improvise a drop test on a customer’s lift.
4. Door circuit test. Open the door at a landing and try to start the car; the car must not move. Try to open the door while the car is between floors; the door must remain locked.
5. Emergency stop test. Press the stop button during travel and confirm the car stops and remains stopped until reset.

Sources used in this section: the page’s specification panel (screw-driven drive, emergency stop, safety sensors, door interlocks, CE, ISO 9001, one-year warranty) and the page’s published description of the anti-sudden-drop design. The general explanation of screw-nut load paths is engineering background, not a model-specific test result.

03 · Specifications

The numbers that decide the layout

The specification panel is the authority for this page. The table below repeats the published values and adds what each one means on site. It does not invent cabin or shaft dimensions; those are not published here.

Unit conversions are arithmetic: 50 ft × 0.3048 = 15.24 m; 400 kg × 2.20462 = 881.8 lb; 0.15 m/s × 196.85 = 29.53 ft/min. The page’s original values remain the specification.

What the table does not tell you

Five dimensions decide whether the lift can be built, and none of them appear in the published specification panel. They are the car’s internal size, the shaft or enclosure size, the pit depth, the overhead clearance, and the door opening. A sixth item, the number of stops, is also missing. Do not let a sales drawing fill those gaps with assumptions.

04 · Travel

What 50 ft of travel demands from the building

Fifty feet is a long way for a residential screw lift. It is also a limit, not a target. The real travel is the vertical distance between the lowest and highest finished floor levels. If the architect’s section shows 15.24 m between those levels, the lift is at the top of its published range. If the section shows more, the project needs a different model.

Long travel changes more than the rail length. It changes the number of rail joints, the fixing pattern, the straightness tolerance, the cable and travelling cable arrangement, the door count, and the time the car spends in motion. Each of those items has to be resolved before the shaft is built.

Measure the right thing

Site measurements taken to a structural slab are not the same as finished floor levels. Tiles, screed, underfloor heating, and thresholds can shift the landing height by tens of millimetres. On a long run, those small differences accumulate into a car that does not line up with the landing. Use the architect’s finished floor levels and confirm them on site before fabrication.

Write down four levels at every stop. The supplier needs all four to set the sills and rail brackets:

• Finished floor level.
• Structural slab level.
• Door threshold level.
• Clear headroom above the landing.

If any level is missing, the drawing is not ready.

Guide rails: straightness is the whole job

A screw lift does not pull the car along a rope. The car is guided by rails, and the nut follows the screw. If the rails are out of plumb, the car will rub, the door will bind, and the nut will carry loads it was not designed for. The rail installation is therefore not a secondary task to be rushed after the car arrives.

Rails should be continuous where the design calls for continuity, with joints staggered so that no two joints sit at the same bracket. Brackets need a structural substrate: a structural wall, a steel frame, or a purpose-made shaft. The fixing pattern, anchor type, and bracket spacing belong on the approved drawing.

Overhead, pit, and the space nobody photographs

The overhead is the space above the top landing; the pit is the space below the lowest landing. Neither dimension is published on this page. A builder who budgets “about a metre” for each is guessing. The approved drawing must give the figures, and the site must be measured against them before the floor is poured or the opening is cut. If the project has no pit, do not assume this model can be installed pitless; ask for a pitless or low-profile variant and get the structural detail in writing.

The lift also adds dead and dynamic load to the building. The approval drawing should show the reactions at the rail brackets and the machine support. If the building is timber-framed or has a lightweight steel mezzanine, ask a structural engineer to check those reactions before fabrication; a long rail run on a flexible wall will amplify vibration.

05 · Power and doors

Backup power, door interlocks, and what happens when the supply fails

The page lists backup power in its published description, but it does not state the backup type, the number of trips it can make, or whether it lowers the car to a landing. Those details change the value of the feature. A battery that only lights the alarm is not the same as a battery that drives the car to the nearest floor and opens the door.

Before you accept the feature, ask for a functional description and a test record. What does the backup actually operate? How long is the switch-over? How many full trips can it make at rated load? What happens when the battery is flat, and how is it tested without taking the car out of service?

There are three common meanings: the backup keeps the alarm or phone dialer alive; it drives the car to the nearest landing and opens the door; or it supports a manual emergency lowering procedure. The first is not a rescue, the second is what most buyers expect, and the third depends on a trained person on site. Find out which one is supplied.

Test the backup under load

A no-load test in the factory proves very little. The test that matters is done on site, with the rated load in the car, with the normal supply isolated, and with the landing doors closed. Record the time to switch over, the landing the car reaches, the door opening time, and the battery voltage before and after. Repeat the test at least once after the battery has been in service for a few months.

1. Confirm the battery and charger are healthy, then load the car to its rated load.
2. Isolate the normal supply at the dedicated isolator, not at the main breaker.
3. Record the switch-over time, the landing reached, the door operation, and the battery voltage.
4. Restore the supply and confirm the charger returns to normal.

Door interlocks are a sequence, not a switch

A door interlock proves the door is closed and locked before the car can move, and proves the car is at the landing before the door can open. A magnet glued to a reed switch is not an interlock; the device should be mechanically actuated by the door lock and monitored by the controller.

Test the sequence at every landing. Open the door and press the call button; the car must not move. Send the car away and try the landing door; it must stay locked. Record the results landing by landing.

06 · Indoor and outdoor

Indoor and outdoor are different projects

The page says the lift can be installed indoors or outdoors. That is a useful range, but it does not mean the same package suits both. An indoor lift sits in a controlled environment. An outdoor lift faces rain, sun, wind, dust, leaves, insects, and temperature swings. The enclosure, finish, drainage, and maintenance plan have to change with the exposure.

What to specify for an outdoor site

Start with the exposure. Is the lift under a roof, against a wall, or fully exposed? Does the site get driving rain, salt air, snow, or strong sun? The answers determine the enclosure finish, the stainless grade, the sealant, and the maintenance frequency. “Outdoor” on a specification sheet is a category, not a material guarantee.

• Roof and canopy. Keep direct rain off the landing and the controller. A canopy that drains onto the landing is worse than no canopy.
• Threshold. Raise the landing threshold above the external paving and slope the paving away from the door.
• Drainage. Provide a sump or drain at the pit. Check that it cannot back up in a storm.
• Fasteners and seals. Use stainless or coated fixings, specify UV-stable seals, and set a replacement interval.
• Controller, battery, and vegetation. Keep the controls dry and ventilated, and keep leaves and insects out of the pit and door track.

Indoors, the common failures are dust, cleaning water, and heat. Keep the pit sump working, do not store paint or cement in the shaft, and give the controller a ventilated position. Protect the door track during the rest of the building works and clean it before commissioning.

07 · Safety and acceptance

What to inspect before the lift is handed over

A residential lift is a small machine, but it still has to be accepted properly. The handover should produce a signed checklist, a set of drawings, a controller fault list, a maintenance schedule, and the certificate documents. A verbal “it’s fine” is not an acceptance record.

The page lists emergency stop, safety sensors, and door interlocks, and states CE and ISO 9001. Those are the published claims. The acceptance process should prove the devices work on this installation and confirm that the documents match the model supplied.

Certification: what CE and ISO 9001 do and do not tell you

CE marking indicates that the product is placed on the market in conformity with the applicable European legislation, as declared by the manufacturer. ISO 9001 is a quality management system standard; it says the supplier has a documented process, not that every lift is identical. Neither document replaces the local building approval, the electrical inspection, or the commissioning test.

Ask for the certificate numbers, the issuing body, the product scope, and the date. Check that the model and the drive type on the certificate match the equipment on site. If the certificate covers a component rather than the complete lift, say so in the handover file. That is not a reason to reject the lift; it is a reason to describe the compliance accurately.

What “levelling” should feel like

At every landing, the car floor and the landing floor should line up within the tolerance stated in the commissioning document. A small step is a trip hazard, and it also points to a landing-detection or rail-alignment problem. Test with the rated load and without it, because the car can sit at a different height when loaded.

Listen during the run. A screw lift is not silent, but it should not bang, scrape, or squeal. A rhythmic click at a rail joint can be normal; a metallic scrape is not. Record the noise and vibration at each landing so that a later change can be compared with the baseline.

Documents to keep

• Approved layout and section drawings, signed by supplier and client.
• Electrical diagram and dedicated circuit details.
• Commissioning record, fault code list, and reset instructions.
• Warranty terms, certificate copies, and the service contact.
• Maintenance schedule and spare-parts list.

08 · Installation

The installation sequence, and what has to be ready first

A screw lift is not difficult to install when the shaft, the power, and the access are ready. It becomes expensive when those items are discovered late. The sequence below is the order that avoids rework. The exact method belongs to the installer; the sequence is what the client and the main contractor need to plan around.

What the client has to provide

• Clear access for the largest component, including the car and the screw column.
• A dry, secure store for equipment before installation.
• Working power and lighting for the installation team.
• A level landing at every stop, with the final floor finish agreed.
• A pit that is clean, dry, and drained, with the specified sump or drain.
• Structural openings and rail substrates built to the approved drawing.
• A safe working area, with edge protection and barriers as required.
• A named person who can approve changes and sign the handover.

What the supplier has to provide

• Approved layout, section, and wiring drawings before fabrication.
• A packing list and a delivery schedule that matches the site programme.
• Installation method, torque values, and the rail-fixing pattern.
• Commissioning records and the controller fault list.
• Certificate copies with numbers and scope.
• Warranty terms and a named service contact in the destination country.
• A spare-parts list with lead times for wear items.

Why installations slip

Most delays come from the building, not the lift: a narrow opening, a floor level that moves after approval, power on the wrong phase, a wet pit, or a finish change after the panels are cut. Freeze the drawing before fabrication and keep a change log. Inspect the site before the order, before delivery, and before commissioning.

Print the 10-point site survey

09 · Maintenance

Maintenance that actually protects a screw lift

The published warranty is one year. A warranty is not a maintenance plan. The screw, nut, rails, doors, and battery need inspection from the first year onward, and the inspection record is what tells you whether the lift is ageing normally or wearing out.

Agree a written schedule with the supplier before handover. The intervals depend on use, environment, and local rules. The list below is the minimum scope to discuss; it is not a substitute for the manufacturer’s manual.

Lubrication: follow the manual, not the hardware store

The screw and nut are a matched pair. The wrong lubricant can attract dust, harden, or attack the nut material. Use the lubricant specified by the manufacturer, apply the specified quantity, and record the date. Do not mix brands or “top up” with a different grease. If the site is dusty or outdoors, the inspection interval may need to be shorter, not the lubricant quantity larger.

What a service visit should produce

• A dated checklist with measured values, not just “OK”.
• Photos of the nut, screw, rails, and door track.
• The controller fault log, with new codes explained.
• Parts replaced, items needing attention, and a signed copy for the household.

Warranty questions to settle before you buy

The page states a one-year warranty. That is the headline. The value depends on the details: which parts are covered, whether labour and travel are included, whether the warranty is honoured in the destination country, and what the exclusions are. Ask for the written terms, not a sentence in a quotation.

• Does the warranty cover the screw, nut, controller, doors, and battery separately?
• Is labour included, and who pays for travel to a remote site?
• What maintenance records are required to keep the warranty valid?
• Is there a local service partner, and what is the response time?

10 · Questions

Questions buyers ask before choosing this model

The answers below use the published values on this page and identify the items that must come from the approved drawing. Where the page is silent, the answer says so.

11 · Quote

What to send, and what the quotation should contain

A useful quotation is a design document, not a price on a postcard. It should state the model, the duty, the car and shaft dimensions, the pit and overhead, the door arrangement, the finish, the safety devices, the certification, the warranty, the lead time, the packing, and the scope of installation. If any of those items is missing, the price is not comparable with another supplier’s price.

What the quotation should state

Questions that expose a weak quotation

Ask what is excluded, who is responsible for the shaft, pit, power, hoisting, and final inspection, and what happens if the site dimensions differ from the drawing. A supplier who can answer those questions has a process.

Specification source: the product specification panel on this page. General engineering explanations are provided for selection and site planning; they are not a substitute for the approved drawing, the manufacturer’s manual, or the local inspection authority. Items marked as requiring confirmation must be confirmed in writing before fabrication.