Winch Drive Series — Building & Construction Vertical Transport

Winch Drive Planetary Gearbox for Lift Elevator

The traction machine gearbox in a passenger or goods lift carries people thousands of times each day in silence — operating in the confined machine room above the shaft with a noise specification that no other winch application demands, an EN 81 safety standard that governs every aspect of its design, and a duty cycle that accumulates millions of start-stop cycles across a 25-year building service life. The winch drive planetary gearbox for a lift must be quieter, more precise, and more fatigue-resistant per unit torque than almost any other industrial gearbox — while fitting in the restricted envelope of the standard lift machine room or, increasingly, the machine-room-less shaft head space.

Korea Ever-Power planetary winch drive gearboxes for lift applications are supplied in the Lift Precision specification — all units include DIN 4 gear accuracy for minimum noise, sub-8 arcminute backlash for floor levelling precision, ratio tolerance of ±0.1% for accurate governor calibration, EN 81-20 brake holding certification at 125% of rated load, EU type examination certificate, and a 20 million cycle gear tooth fatigue rating as standard. All units use helical planetary stages with a minimum 18-degree helix angle for maximum noise reduction.

The ZL55 compact series covers residential and small commercial lifts up to 630 kg rated load. The ZR75 and 407AW cover the full commercial passenger lift range. The 414W3 series handles heavy goods lifts and construction hoists where sustained high-torque operation accompanies the noise and precision requirements of the lift application category.

Achieving less than 48 dB(A) from a planetary gearbox transmitting several kilowatts of power to a traction sheave is an engineering challenge that requires coordinated design across the gear mesh geometry, gear accuracy, housing stiffness, bearing selection, and lubricant viscosity. Korea Ever-Power applies the following noise reduction measures specifically for lift traction gearboxes:

High Helix Angle Helical Gears (18–22 degrees): The helix angle of the planet gear determines the contact ratio in the face width direction — the fraction of face width that is simultaneously in contact across the gear mesh. A higher helix angle increases this contact ratio, smoothing the load transfer between successive tooth pairs and reducing the excitation force at the gear mesh frequency. Korea Ever-Power lift gearbox planet stages use 18 to 22 degree helix angles — higher than the 15 degrees used in standard industrial applications — increasing the face contact ratio to above 1.8 and reducing the gear mesh force ripple by approximately 40% compared to equivalent spur gears.

DIN 4 Gear Accuracy and Profile Crowning: In addition to DIN 4 profile and pitch accuracy, lift traction gearbox gears receive a light profile crowning — a deliberate, controlled convex modification of the tooth profile that concentrates the load at the pitch line and reduces the edge loading that generates high-frequency mesh noise at the tooth mesh entry and exit points. The crowning depth is between 3 and 6 microns on the planet and sun gear profiles — small enough to maintain the rated load capacity, large enough to eliminate the edge stress concentrations that amplify mesh noise.

Damping Ring Gear Mount: The ring gear in a standard planetary gearbox is rigidly pressed or splined into the gearbox housing — providing a direct transmission path for gear mesh vibration from the gear teeth to the housing exterior, where it radiates as airborne noise. Korea Ever-Power lift gearboxes use a ring gear mount with a rubber-metal isolation layer between the ring gear outer diameter and the housing bore — attenuating the gear mesh vibration transmission path by 6 to 12 dB(A) before it reaches the housing surface. This damped mounting approach is the single most effective noise reduction measure at the system level.

Passenger lift ride comfort is quantified by the vibration level in the car — specifically the peak acceleration in the vertical direction during rated speed travel, measured in milli-g (mg). A ride with less than 20 mg vertical vibration is imperceptible to passengers; 20 to 50 mg is detectable but acceptable; above 50 mg generates complaints. The planetary gearbox contributes to in-car vibration through two mechanisms:

Gear Mesh Vibration Transmission: The gear mesh force ripple at the gear mesh frequency — which for a 20:1 ratio gearbox with a 3-planet carrier running at 1,500 rpm motor speed produces a mesh frequency of 1,500/20 x 3 = 225 Hz — transmits through the traction sheave, wire ropes, and car frame as structural vibration. Korea Ever-Power lift gearbox damped ring gear mounting attenuates this transmission by 6 to 12 dB, reducing the in-car vertical vibration contribution from the gear mesh to below 5 mg — leaving adequate vibration budget for the rope, sheave, and guide rail contributions.

Floor Levelling Precision: At the end of each trip, the lift car must level to within ±5 mm of the floor landing — the tolerance required for safe and comfortable entry and exit. The VFD decelerates the motor, the car approaches the landing, and at the final positioning stage the motor creeps at 5 to 15 % of rated speed for the last 100 to 200 mm of travel. Any backlash in the traction gearbox causes the car to judder during this creep phase — the motor advances, the backlash absorbs the movement, and the car does not move until the backlash is taken up. Sub-8 arcminute backlash in the Korea Ever-Power lift gearbox eliminates this judder, producing smooth, continuous car movement through the entire levelling approach and landing within the ±5 mm requirement.

Encoder Compatibility for S-Curve Profiling: Modern VFD lift controllers use S-curve velocity profiling — a trapezoidal velocity profile with sinusoidal jerk limiting at the acceleration and deceleration transition points — to minimise the jerk sensation perceived by passengers during speed change. The motor encoder provides the velocity feedback for S-curve tracking. Korea Ever-Power lift gearboxes include a precision encoder mounting provision concentric with the motor input shaft to within 0.01 mm TIR, compatible with all major lift VFD encoder types and resolutions — ensuring that the encoder reads true motor velocity without eccentricity-induced velocity ripple that would corrupt the S-curve tracking and generate perceptible jerk at speed transitions.

Korea Ever-Power lift traction gearboxes undergo a five-stage factory acceptance test that addresses the noise, precision, safety, and fatigue requirements specific to the lift application:

Noise Measurement: Run at rated speed and 60% rated torque in a semi-anechoic test enclosure. A-weighted sound pressure level measured at 1 metre in four quadrant positions. Maximum reading recorded and compared to the model-specific noise limit. Units exceeding the noise limit are returned for gear set inspection before re-test — the most common cause of noise limit exceedance is planet set tooth thickness mismatch that increases the load sharing variation between planets and amplifies the mesh frequency excitation.

Backlash Measurement: Measured using a precision rotary encoder as described for warehouse applications. Must be below 8 arcminutes. For residential lift gearboxes with a 48 dB(A) noise target, an additional backlash test is conducted at two operating temperatures — at 20°C (cold) and at 80°C (hot) — to verify that thermal expansion of the housing does not reduce backlash to zero at operating temperature, which would cause gear bind and a step increase in noise.

Brake Holding Test: Static hold at 125% rated load in both the upward and downward directions with motor de-energised. Zero car movement required. Brake disc temperature recorded. This test directly verifies EN 81-20 Clause 12.4 compliance and is recorded in the type examination dossier maintained by the notified body.

Vibration Measurement: Run at rated speed with dummy load equivalent to rated car load. Tri-axial accelerometer mounted on the output shaft housing. Peak-to-peak vibration at rated speed recorded in three axes. Vertical axis vibration must remain below 15 mg to ensure the in-car contribution stays within the 30 mg total vertical vibration budget, allowing the rope, sheave, and guide rail contributions to account for the remaining 15 mg budget.

Korea Ever-Power lift application engineers provide free traction machine gearbox sizing for lift projects — confirming EN 81-20 compliance, calculating the 20-year fatigue life at the specified duty cycle, and providing noise measurement data for building acoustic analysis. For construction hoist applications, we provide the EN 12159 compliance documentation required for temporary equipment approval on EU construction projects. Contact us with your car rated load, travel speed, duty cycle, and building type for a free compliance review and gearbox proposal within 48 hours.

Source Your Lift Elevator Winch Drive Planetary Gearbox

Whether you are designing a new traction lift machine, specifying replacement gearboxes for a lift modernisation project, or commissioning a construction hoist for a new building project — Korea Ever-Power delivers EN 81-20 compliant, sub-48 dB(A) noise rated, 20 million cycle life planetary winch drive gearboxes built for the precision, safety, and quietness that building lift applications demand. Send us your car rated load, travel speed, building type, and noise specification for a free compliance review, acoustic analysis, and gearbox proposal within 48 hours.