Material Skip Hoist

Overview

A material skip hoist lifts loose material, concrete, mortar, screed or demolition rubble, up the outside of a building in a tipping skip. It is a goods-only hoist: no person rides it, and it is designed to load at the bottom, lift, and discharge automatically at the top. On a concreting or demolition job it keeps a steady flow of material moving without a crane, at much lower cost and set-up effort than a passenger-and-goods hoist.

The skip runs on a guide tower that can be vertical against a facade or inclined like a ladder against scaffold. Capacity is modest, 150 to 500 L of material per lift, but the cycle is fast: load, hoist, tip, return. The hoist suits the repetitive vertical transport of bulk material that would otherwise be carried by hand or barrow.

Guide Tower

The Guide Tower carries the skip and reacts its load. It is built from bolted Tower Mast Section lattice sections stacked to set the lift height, with Skip Guide Rail guide rails down the working face for the skip carriage rollers and Tower Base Foot feet anchoring the tower to a concrete base, fixed with a Fastener Set. Because the loaded skip puts an eccentric and cyclic load into the tower, Tower Tie Frame tie frames brace it to the building or scaffold against sway and wind at intervals up its height.

Tipping Skip Carriage

The Tipping Skip Carriage is the part that moves. Its Skip Bucket Body welded steel bucket holds 150 to 500 L of concrete, mortar or rubble and carries a replaceable Skip Wear Liner wear liner because abrasive material wears the bucket fast. The bucket pivots on a Skip Tip Pivot hardened pin mounted in a Roller Carriage Frame roller carriage, and four Carriage Guide Roller flanged rollers run on the tower guide rails to hold the carriage square as it climbs. Holding the skip on a pivot is what lets it travel upright and then rotate to discharge at the top without any powered tipping actuator.

Hoist Winch and Roping

The Hoist Winch raises the skip. A Hoist Motor motor drives a Winch Gearbox reduction gearbox, built from a Gearbox Housing casting, a Helical Gear Pair reduction and an Oil Seal seal, which turns a Hoist Rope Drum grooved drum carried on Ball Bearing bearings. A Hoist Holding Brake spring-applied brake holds the skip on the rope at any height if power is lost.

The Wire Rope & Sheaves connects winch to skip. Hoist Wire Rope hoist rope runs from the drum over Deflection Sheave deflection sheaves and the Tower Head Sheave head sheave at the tower top, then down to the carriage where it is fixed with a Rope Termination wedge socket. Single-layer drum grooving keeps the rope spooling cleanly so it does not cross-wind under the cyclic loading.

Tipping Mechanism

The Skip Tipping Mechanism discharges the skip automatically at the head with no power and no operator action. A Travel Latch travel latch holds the bucket upright during the lift. As the carriage reaches the top, a Tip Cam Roller roller on the skip meets a fixed Tip Trip Ramp trip ramp, which forces the bucket to rotate about its pivot and tip the load into the discharge point. When the carriage descends, a Coil Spring return spring rights the bucket and the latch re-engages for the next cycle. The whole tip-and-return is purely mechanical, driven by the carriage position.

Loading Hopper

At the base, the Loading Hopper feeds the skip. A sloped Hopper Body receives concrete or rubble at ground level, a Protective Grate grate keeps oversize lumps and hands out, and a Discharge Chute chute with a Loading Gate gate directs material into the skip when it is parked at the bottom. The operator fills the hopper, the skip indexes to the load point, the gate opens, and the lift cycle begins. This arrangement lets a barrow or pump charge the hopper continuously while the hoist runs.

Control and Safety

The Control & Safety System system runs the hoist as a goods-only machine. A Operating Control Panel gives hold-to-run up, down and stop, so the operator must keep a hand on the control for the skip to move. Travel Limit Switch limit switches stop the skip at the bottom load point and the top tip point, and a Slack-Rope Switch slack-rope switch cuts the drive if the rope goes slack, which prevents a fouled or birdcaged re-start. Interlocked Landing Gate interlocked landing gates at the load and discharge levels are tied into the motion so the hoist cannot run with a gate open, an Emergency Stop emergency stop cuts all power, and Wire Bundle wiring links the controls. Because no person rides the skip, the hoist is built to the goods-only material-hoist standard rather than the stricter passenger-rated code, but the no-rider rule, the gate interlocks and the limit and slack-rope protection are all enforced for the crew working around the base and head.