A cable hoist and conveyer is a powered drum-and-sheave system that winds wire rope to lift, lower, or traverse loads vertically and horizontally on a construction site. The Alimak SE-H series mast-climbing material hoist uses exactly this arrangement to deliver bricks, mortar, and rebar up high-rise cores. The drum motor reels rope onto a grooved barrel while sheave blocks redirect the rope along the travel path, multiplying mechanical advantage. Result: a single 7.5 kW gear motor moves 1,000 kg loads 60 m up at 30 m/min, replacing a dozen tower-crane lifts per shift.
Cable Hoist and Conveyer Interactive Calculator
Vary the load and number of supporting rope falls to see rope tension, capacity multiplier, and hook speed tradeoff.
Equation Used
The worked example shows a 2-part reeving hoist: two rope falls support the hook block, so each fall carries half the load. In general, n supporting falls give rope tension T = W/n and hook speed equal to rope speed divided by n.
- Ideal reeving with equal load sharing in all rope falls.
- Friction, sheave bearing losses, drum inertia, and rope weight are neglected.
- Load mass is converted to force using standard gravity.
Inside the Cable Hoist and Conveyer
A cable hoist runs on three jobs happening at once — torque conversion, rope spooling, and load redirection. The motor delivers torque through a worm or planetary gearbox down to a grooved drum. The drum winds the wire rope at a controlled rate, and the rope passes over one or more sheaves (pulleys) that change direction and add mechanical advantage through reeving. Reeving just means how many rope falls support the hook block — 2-part reeving doubles your lift capacity for the same drum pull but halves your hook speed. Same total energy, traded between force and velocity.
The geometry has to be right or the rope eats itself. The fleet angle — the angle between the rope leaving the drum and the line perpendicular to the drum axis — must stay under 1.5° for grooved drums and under 2° for smooth drums. Go past that and the rope starts climbing the previous wrap, crushing the strands and shortening rope life from the typical 3-5 years down to a few months. The drum diameter to rope diameter ratio (D/d) must be at least 18:1 for construction hoist duty per ASME B30.7. Drop below that and bend fatigue kills the rope from the inside out — you won't see it until a strand pops.
Failure modes are predictable. Fleet angle wrong: bird-caging and broken outer wires. D/d too small: internal wire breaks under the strands. Drum overspooled past its rated layers: rope crushes itself on the lower wraps. Sheave groove worn oversize: rope flattens and core gets exposed. A daily pre-shift inspection of the rope at the dead-end and the equalizer sheave catches 90% of these before they fail.
Key Components
- Drum (Barrel): Grooved steel cylinder that spools wire rope under tension. Groove pitch must match rope diameter within +0.07d / -0 — too tight and the rope binds, too loose and it cross-winds. Typical construction hoist drums run 250-500 mm diameter for 8-13 mm rope.
- Wire Rope: 6×36 IWRC (Independent Wire Rope Core) is the standard for construction hoists — 6 strands of 36 wires around a steel core. Minimum breaking force must give a 5:1 design factor on rated load per ASME B30.7. An 8 mm 6×36 IWRC rope breaks at roughly 4,400 kg, so it gets rated for 880 kg working load.
- Sheave Block: Grooved pulley that redirects rope and multiplies mechanical advantage. Groove radius must be 1.06 to 1.10 × rope radius. Tighter pinches the rope, looser flattens it. Sheave bearings on a hook block need re-greasing every 100 hours under construction-site dust loading.
- Gearbox: Worm or planetary reducer between motor and drum. Worm gives 30:1 to 60:1 single-stage reduction with self-locking holdback — load won't backdrive if power is lost. Planetary gives higher efficiency (95% vs 70%) but needs a separate brake.
- Holding Brake: Spring-applied, electrically released disc or band brake on the motor input shaft. Sized to hold 150% of rated load static. Brake torque must release within 50 ms of contactor close or the motor stalls against the brake on startup — burns out the contactor coil within a few hundred cycles.
- Limit Switches: Upper and lower travel limits, plus a slack-rope cutout. The upper limit must trigger with at least 2 full wraps of rope still on the drum — those dead wraps anchor the load. Lose them and the rope clamp takes the full load, which it isn't rated for.
- Conveyer Trolley or Mast Carriage: On a mast-climbing material hoist this is a guided car running on a rack-and-pinion mast or a guide-roller channel. The cable hoist lifts the carriage; the mast keeps it from swinging. Roller clearance to mast is 1.0 to 1.5 mm — tighter binds, looser lets the carriage rock and shock-load the rope.
Who Uses the Cable Hoist and Conveyer
Cable hoist and conveyer systems show up anywhere a jobsite needs vertical material flow without tying up a tower crane. The duty cycle matters more than the peak load — a hoist running 100 lifts per shift needs M5/M6 FEM classification, while a tower-mounted personnel hoist on a 40-storey core might run M7. Pick the wrong duty class and the motor cooks out in 6 months. You also see them as conveyer drives — the cable becomes the haul line on a chain-bucket aggregate elevator or an inclined skip hoist feeding a concrete batch plant.
- High-Rise Construction: Alimak Scando 650 mast-climbing material and personnel hoist on the One Vanderbilt build in Manhattan — moves crews and bagged material up 427 m at 65 m/min.
- Concrete Batching: Liebherr Mobilmix 2.5 batch plants use a cable-driven skip hoist to lift aggregate from the ground bin to the mixer charging chute, typically 15-25 m lift at 2,500 kg per cycle.
- Underground Mining: Koepe friction hoists at the Kidd Creek mine in Ontario run wire rope cages 2,000+ m down the shaft at 18 m/s — same drum-and-sheave principle scaled up.
- Bridge Construction: Form-traveler hoists on the Champlain Bridge replacement in Montreal carried segmental formwork forward span by span using twin synchronized cable winches rated 50 t each.
- Low-Rise Residential: Maeda MC-305C mini crawler crane with cable winch lifting roof trusses on framing crews — 2.9 t at 3 m radius, fits through a 600 mm gate.
- Industrial Roofing: GEDA 250 Comfort cable hoist mounted on a parapet jib lifting rolled membrane and ballast onto flat commercial roofs, 250 kg at 30 m/min.
- Shipyard Block Assembly: Konecranes shipyard goliath cranes use multi-fall cable reeving to lift 600-900 t hull blocks during megablock erection.
The Formula Behind the Cable Hoist and Conveyer
The fundamental sizing question on a cable hoist is: given my motor, drum, and reeving, how fast does the load move and how much can it lift? Hook speed and hook force trade against each other through the number of rope falls. At the low end of typical construction reeving (1-part, single fall) you get full drum speed at the hook but the lift capacity equals the rope's working load — fast and light. At the high end (4-part reeving) you get a quarter of the speed but four times the capacity — slow and heavy. The sweet spot for most material hoists is 2-part: doubles capacity, halves speed, and the hook block stays compact enough to fit through a typical 1.2 m × 2.4 m loading bay opening.
Variables
| Symbol | Meaning | Unit (SI) | Unit (Imperial) |
|---|---|---|---|
| vhook | Hook (load) lifting speed | m/s | ft/min |
| Ddrum | Pitch diameter of rope on the drum (drum OD + rope d) | m | in |
| Ndrum | Drum rotational speed | rev/s | RPM |
| nparts | Number of rope falls supporting the hook block (reeving) | — | — |
| Fhook | Maximum hook lifting force | N | lbf |
| Tdrum | Torque at the drum shaft | N·m | lbf·ft |
| η | Reeving efficiency (≈0.98 per sheave on rolling bearings) | — | — |
Worked Example: Cable Hoist and Conveyer in a precast panel hoist on a tilt-up warehouse build
Sizing a cable hoist and conveyer for lifting precast wall-panel formwork accessories on a 14 m tilt-up distribution warehouse build in Reno, Nevada. The crew uses a GEDA 500 Z/ZP cable hoist mounted on a wall-mounted jib at the edge of the slab, reeved 2-part to lift bracing hardware, embed plates, and bagged grout from the ground laydown to the slab edge. Drum diameter is 0.30 m at the rope pitch line, drum runs at 36 RPM nominal off a 5.5 kW motor through a 30:1 worm reducer, drum rated torque 1,200 N·m, two-sheave hook block efficiency 0.96, 8 mm 6×36 IWRC rope.
Given
- Ddrum = 0.30 m
- Ndrum = 36 RPM
- nparts = 2 —
- Tdrum = 1200 N·m
- η = 0.96 —
Solution
Step 1 — convert drum speed to rev/s for SI units:
Step 2 — at nominal 2-part reeving, compute hook speed:
Step 3 — compute hook lifting force at nominal:
Step 4 — at the low end of the typical reeving range for this hoist class, 1-part single fall:
That's fast — almost too fast for a hand-loaded skip with loose material on it. Above 30 m/min on an open hook the load starts swinging on stop, and the operator gets behind on the brake button. Crews typically use 1-part only for empty rigging trips back down.
Step 5 — at the high end, 4-part reeving:
At 8.5 m/min the load creeps — fine for a one-shot heavy pick like dropping a 3 t precast brace stack onto the slab, but useless for a 200-cycle shift moving small bundles. The 2-part nominal at 17 m/min and 1,565 kg sits in the sweet spot for this jobsite's mixed-load duty cycle.
Result
Nominal hook speed is 0. 283 m/s (17 m/min) at a hook capacity of roughly 1,565 kg with 2-part reeving — that's a comfortable working pace where the operator can land a load on the slab edge without overshoot, and the capacity covers everything the framing crew sends up except a full pallet of grout. Compare that to 34 m/min and 783 kg at 1-part (too fast for loaded picks, fine for empties) and 8.5 m/min at 3,130 kg at 4-part (heavy single-shot work only) — the 2-part sweet spot wins for this duty cycle. If you measure 12 m/min at the hook instead of the predicted 17, three causes dominate: (1) the worm gearbox is overheated and slipping below rated efficiency — feel the case, anything over 80°C means the lubricant has thinned and you're losing torque-speed product, (2) the drum brake is dragging because the spring-released coil isn't pulling the disc fully clear, typically a worn solenoid plunger, or (3) rope cross-winding on the drum has reduced effective pitch diameter — check fleet angle and drum groove wear.
Cable Hoist and Conveyer vs Alternatives
Cable hoist isn't the only way to move material vertically on a jobsite. Rack-and-pinion hoists and hydraulic mast lifts compete for the same duty. The choice comes down to lift height, duty cycle, and what you're willing to spend on the mast structure.
| Property | Cable Hoist & Conveyer | Rack-and-Pinion Hoist | Hydraulic Mast Lift |
|---|---|---|---|
| Typical lift speed | 15-90 m/min | 12-100 m/min | 5-15 m/min |
| Maximum practical lift height | 60-100 m on single drum, 600+ m on Koepe friction | 300-400 m mast-climbing | 20-30 m |
| Load capacity range | 250 kg to 50,000 kg+ | 500 kg to 5,000 kg per car | 200 kg to 2,000 kg |
| Capital cost (small-jobsite class) | $3,000-$15,000 | $25,000-$80,000 | $8,000-$20,000 |
| Maintenance interval | Rope inspection daily, replace 3-5 yr | Pinion and rack greasing weekly, replace 5-10 yr | Hydraulic fluid change yearly, seal kit 2-3 yr |
| Failure mode if neglected | Wire rope strand failure (catastrophic) | Pinion tooth wear (gradual, audible) | Seal blowout, controlled descent |
| FEM duty classification range | M3 to M8 | M5 to M7 typical | M3 to M5 |
| Best application fit | Variable-load mixed-duty material handling | High-cycle personnel + material on tall buildings | Low-rise interior fitout, slow heavy single picks |
Frequently Asked Questions About Cable Hoist and Conveyer
Check the dead-end anchor first. On a 2-part reeve one rope fall is dead-ended to the becket on the upper block, and the other runs back to the drum. If somebody re-rove the system and tied the dead end to the lower (hook) block instead of the upper, you've accidentally created a 3-part inefficient reeve — the hook moves at one-third drum payout instead of one-half.
The other common cause is reeving through a sheave that doesn't turn. If a hook-block sheave bearing has seized, the rope drags across a stationary groove and the system behaves like a fixed redirect — you lose the velocity-multiplying action of that pulley. Spin each sheave by hand with the load off. Anything that doesn't turn freely under finger pressure is a problem.
6×19 has fewer, thicker outer wires — better abrasion resistance but worse fatigue resistance. 6×36 has more, thinner wires for the same rope diameter — better bend-fatigue life but the outer wires nick more easily on rough sheaves or drum lips.
Rule of thumb: if your rope spends most of its life cycling over sheaves (typical hoist duty with multiple bends per lift), pick 6×36 IWRC. If the rope drags over edges, masts, or rough surfaces (winch-line work, pulling sleds), pick 6×19 IWRC. Construction mast hoists are bend-dominated, so 6×36 wins on service life by a factor of 2-3× in real jobsite data.
Crossover is around 600-800 m of lift. Below that, a drum hoist is simpler and cheaper — one drum, one rope, one motor. Above that, the rope weight itself becomes the dominant load on the drum, and you'd need an absurdly large drum to spool it all without exceeding layer count limits (typically 4 layers max for safe spooling).
Koepe (friction) hoists drive the rope by friction against a grooved drive sheave with a balance rope on the other end, so neither end is spooled — the rope just translates. Mining shafts past 800 m almost universally use Koepe. Construction rarely sees lifts deep enough to justify it, but bridge tower interiors and chimney work occasionally do.
Dynamic load amplification. Rated capacity is the static load. The moment you start a lift, rope stretch and motor inrush combine to produce a peak rope tension 1.3-1.8× the static load for the first 0.2-0.5 seconds. If your load cell or motor-current overload is set to trip at 110% of static rated, a 90% static lift can spike past 110% dynamically.
Two fixes: ramp the soft-starter slower (extend acceleration from 1 s to 3 s and the dynamic peak drops by roughly 40%), or raise the overload trip setpoint to 130% with a 1-second time delay. Don't disable it — the overload is also your shock-load protection if a load snags during lift.
Localized breaks at a fixed rope position mean the damage source is fixed in space, not in the rope. The rope is the victim. Look at the upper sheave groove first — if the groove radius is worn oversize (more than 1.10 × rope radius) the rope flattens against the bottom of the groove and the outer wires fatigue at that bend point on every cycle.
Other suspects: a chipped flange on the sheave, a misaligned equalizer that puts side-load on the rope as it enters the sheave, or a foreign object lodged in the groove. Replace the sheave, then replace the rope — running a new rope on a damaged sheave just kills the new rope at the same spot.
Yes, oversize the drum within reason — going from a 16:1 D/d ratio to 30:1 roughly triples bending fatigue life of the rope. But oversizing has real costs: drum mass scales with D², drum inertia scales with D⁴, and the motor has to accelerate that inertia every start-stop cycle. On a high-cycle hoist (M7 duty, 200+ starts per hour) you can spend more energy spinning a giant drum up and down than you save on rope wear.
Sweet spot for construction material hoist drum-to-rope ratio is 20:1 to 25:1. That gives 5-7 year rope service at typical duty without making the drum a flywheel.
References & Further Reading
- Wikipedia contributors. Hoist (device). Wikipedia
Building or designing a mechanism like this?
Explore the precision-engineered motion control hardware used by mechanical engineers, makers, and product designers.
