Motion control for lifts, cranes and hoists

In short:Lifts, cranes and hoists move people and heavy loads, so their motion components are chosen around safety rules first: EN 81-20 for lift doors and car movement, EN 81-41 for platform lifts, ISO 4301 duty classes for crane mechanisms, and LOLER examinations in service. The core parts are encoders on the motor, brake and shaft, door drives, slip rings for slewing and cable reels, and hoist gearboxes sized for the duty class.

Typical requirements

Machinery we specify motion for

• Traction lift main motors
• Lift door operators
• Lift brake monitoring
• Lift shaft position systems
• Escalators
• Tower, mobile and loader cranes
• Marine and offshore cranes
• Hoists and winches
• Wheelchair platform and ramp lifts
• Hose and cable reels

What lifts, cranes and hoists demand from motion components

Lifting equipment carries people and heavy loads over people, so every motion component is chosen against a safety rule before it is chosen on performance. A lift door drive is limited by how much energy the door may carry. A hoist gearbox is sized by how many hours it will spend at what fraction of full load. A crane slew encoder feeds the device that stops the crane overturning. And in the UK, the finished equipment is examined in service under LOLER: every 6 months for people-lifting equipment and lifting accessories, every 12 months for other lifting equipment, unless an examination scheme says otherwise.

The duty is also long. A lift or crane mechanism may run for decades, often outdoors or in a shaft that is hard to reach, so ease of inspection and diagnostic data matter as much as the headline rating.

Where each component sits: lifts, cranes and hoists

Lift motors, brakes and shaft position

HEIDENHAIN splits lift feedback into four jobs: motor control, brake monitoring, shaft position and door motors. It names an incremental encoder as its standard lift motor encoder, an inductive encoder that detects brake stroke and temperature without extra microswitches (tied to unintended car movement monitoring), absolute encoders for digital shaft copying so the car can go straight to its destination after a power cut, and compact door-motor encoders under 40 mm diameter. One shaft encoder option carries up to 150 N axial and 350 N radial load.

Gearless machines run slowly. A published WEG gearless machine covers 3.5–11 kW, S3 40% duty, IP54, with an integrated brake and an EnDat encoder. Low speed means the encoder needs high resolution for smooth control near zero speed. For OEM-built machines, frameless kits such as the ADR-P (110–360 mm, up to 365 Nm continuous) or the in-runner TI Series can be built around the sheave. See frameless torque motors.

Lift door operators

Under EN 81-20, the door and its rigidly connected parts must stay at or below 10 J kinetic energy at average closing speed, and 4 J with an audible warning if the protective device has failed. The detection device must cover 25 to 1,600 mm above the sill and detect a 50 mm obstacle. That is why door operators have moved to brushless motors with encoders and a positioning controller: the drive must shape the speed profile to the door’s mass. maxon’s door drive developed with Schindler uses a 90 mm brushless flat motor with an on-board encoder and a controller that calibrates door size and weight, moving doors up to 400 kg in its belt-drive version.

Cranes, slewing and cable reels

rotarX lists the slew connection on mobile cranes, cable reels on gantry and harbour cranes, tower cranes, pillar jib cranes and attachments such as grabs as slip ring uses. Power levels are high: one published tower crane slip ring is quoted at 900 A and 380 V on six rings. Our pages on slip rings for cranes and slewing and slip rings for cable reels go into circuit design. For high currents, start from the carbon-brush BHR Series; for slew and reel units with data channels, the RF Integrated / Cable Reel Slip Ring range.

Mobile cranes rely on a rated capacity limiter, and rated capacity indicator systems such as Trimble’s take inputs from angle, length and slew sensors to warn the operator as the crane nears its rated capacity. The EN 13000 amendment reported by KHL limits operating speed to 15% when the limiter is overridden. A slew encoder that fails or slips therefore affects a safety function, not just a display. Choose one with diagnostics, mount it so the gear mesh cannot jump a tooth, and give the control system a way to detect a frozen or implausible reading.

Escalators and hose reels

Escalators use the same building blocks as lifts: a main drive motor and brake, with speed feedback to the control and safety system. Hose and cable reels on fire appliances, process plant and travelling cranes need a slip ring or rotary union on the reel axis and a reel drive that keeps tension without overrunning. Where a reel carries both fluid and power, a combined unit saves space; see rotary unions.

How to size a hoist: worked example

A wire rope hoist lifts 1,000 kg at 8 m/min on two-fall reeving with a 200 mm drum, running about 2 hours a day at a medium load spectrum.

1. Rope pull: 1,000 × 9.81 / 2 falls = about 4,900 N.
2. Drum torque: 4,900 N × 0.1 m = 490 Nm.
3. Drum speed: rope speed is 16 m/min with two falls; 16 / (π × 0.2) = about 25 rpm.
4. Ratio: with a 1,500 rpm motor, about 59:1.
5. Power: 1,000 × 9.81 × (8/60) = 1.31 kW at the hook; at an assumed 85% drivetrain efficiency, about 1.5 kW at the motor. Add acceleration torque.
6. Duty class: under ISO 4301-1, 1–2 hours of daily running is utilisation class T4 (3,200 h design life) and 2–4 hours is T5 (6,300 h). Combine the class with the load spectrum (L1–L4) to get the mechanism group, M1–M8, and apply the gearbox maker’s service factor for that group.
7. Brake: the brake on the motor must hold the load with margin; check the gearbox can carry that braking torque at its output.
8. Feedback: a multi-turn absolute encoder on the drum, such as the VLM, keeps hook position through a power cut.

Platform lifts and ramps

EN 81-41 covers powered vertical lifting platforms for people with impaired mobility: rated speed no more than 0.15 m/s and a path within 15° of vertical. At those speeds a 12/24 V screw actuator such as the GT44 (6,000 N push) or a geared motor and screw is a common drive. Check duty cycle, manual lowering on power loss and outdoor sealing. See how to size a linear actuator.

Typical pitfalls

1. Sizing a hoist gearbox on peak load only and ignoring the mechanism class and running hours.
2. No spare slip ring circuits. Cameras, anti-collision systems and wind sensors get added later.
3. Incremental slew or drum feedback that needs re-homing after a power cut with a load on the hook.
4. Door drives tuned for one door mass. EN 81-20 energy limits must hold across the whole range.
5. Forgetting the examination regime. Make brakes, slip rings and encoders easy to inspect.

Send us the load, speeds, duty class, supply and environment, and our specialist engineering and supply partners will propose matched encoders, slip rings, motors, gearboxes and drives.

Standards to have in view

• BS EN 81-20:2020 (passenger and goods passenger lifts)
• EN 81-50 (lift component design rules, calculations and tests)
• BS EN 81-41 (vertical lifting platforms for persons with impaired mobility)
• ISO 8100 series (lifts, international successor work to EN 81)
• ISO 4301-1 and FEM 9.511 (classification of cranes and mechanisms)
• EN 13001 series (cranes: general design)
• EN 13000 (mobile cranes) and ISO 10245 (crane limiting and indicating devices)
• ISO 13849-1 (safety-related parts of control systems)
• LOLER 1998 (UK Lifting Operations and Lifting Equipment Regulations)

Which standards apply depends on the end product and its market. Your engineer will confirm what the component itself needs to meet.