Mechanized Scaling Rig

Overview

A mechanized scaling rig removes loose and fractured rock from the roof, called the back, and the walls of an underground excavation before workers and equipment move in. After a blast the freshly exposed rock is full of cracks, and slabs hang ready to fall. Hand scaling with a bar is slow and puts a person directly under the hazard. This rig does the same job from a protected cab: a heavy steel pick on a long articulated boom pries the loose rock down while the operator sits behind a falling-object canopy, set back from the fall zone.

The machine is built around four things working together. The Carrier Chassis drives the rig to the face and plants it. The Scaling Boom reaches the pick up to the back and out along the walls. The Scaling Head carries the pick and, when rock will not come down by prying, a hydraulic breaker. The Operator Cab keeps the operator safe from the material the rig is deliberately bringing down. A Hydraulic System pack powers every motion and a Electrical System system lights the face and runs the controls.

Carrier and chassis

The Carrier Chassis is an articulated wheeled frame split into a Front Frame Section and a Rear Frame Section joined by a Articulation Joint. Two Steering Cylinder units bend the frame to steer, which lets a long machine turn inside tight drifts where a fixed-frame vehicle could not. Drive comes from a Diesel Engine of around 75 kW, fitted with a Exhaust Catalytic Scrubber because the engine runs in confined air. Power passes through a Powershift Transmission to two Drive Axle units with planetary hubs and wet disc brakes, then to four Wheel & Tire assemblies on foam-filled tires that cannot go flat on sharp muck. Before scaling, four Stabilizer Leg outriggers drop and plant the rig so the boom reactions do not rock it.

Scaling boom

The Scaling Boom is the reach of the machine. It is a three-section weldment in abrasion-resistant plate: a Boom Base Section, a Boom Mid Section, and a telescoping Telescoping Boom Tip that extends the last stretch to the rock. A Slew Ring Bearing swings the whole boom left and right. A Lift Cylinder raises and lowers it, a Extension Cylinder pushes the tip out, and a Head Tilt Cylinder angles the head against the surface. The joints ride on hardened Boom Pivot Pin pins turning in bronze Boom Pivot Bushing bushings, which take the shock of repeated prying without seizing. Reach is typically 8 to 9 m up and 9 to 10 m out, enough to scale the back of a large heading from a single setup.

Scaling head

The Scaling Head is where the work happens. The primary tool is the Scaling Pick, a forged spike held in a Pick Holder Block. The operator drives the pick into a crack behind a loose slab and levers it free with the boom. A Head Rotator turns the head so the pick can attack a crack from the best angle. When a slab is keyed in too tightly to pry, the Hydraulic Breaker, a hydraulic impact hammer, delivers 1,200 to 1,700 J per blow through a Breaker Moil Point to crack it loose. For sheeting that peels off a face in flat layers, a Scaling Rake combs the loose material down in one pass. The head mounts on hardened Head Mount Pin pins.

Operator cab

The Operator Cab is the safety case of the whole machine. Its job is to protect the operator from the very rock the rig is knocking down. A FOPS Canopy rated to ISO 3449 stops falling objects, and the ROPS Cab Frame meets ROPS standard ISO 3471 against a rollover. Inside, a Suspension Seat on a sprung Coil Spring suspension isolates the operator from the jolts of breaking, and two Control Joystick controllers work the boom and head. The cab sits offset from the boom centerline so the operator is never directly beneath the fall zone, and laminated Laminated Cab Glass gives a clear view of the face while a Cab HVAC Unit unit keeps the air breathable in deep, hot workings.

Hydraulics and electrical

The Hydraulic System pack supplies every cylinder and motor on the machine. A variable Variable Displacement Pump draws from the Hydraulic Tank and feeds a Proportional Valve Bank of proportional spools that meter oil to the boom, head, steering, and outriggers. System pressure runs 210 to 250 bar, watched by Pressure Sensor units, and a Oil Cooler sheds the heat of continuous breaking. The Electrical System system is 24 V: a Machine Control Unit coordinates the functions, a 12 V Battery pair and Alternator supply power, and six LED Work Light lamps flood the face so the operator can read the rock.

Variants and use

A scaling cycle is straightforward. The operator trams in, drops the Stabilizer Leg outriggers, and works the pick across the back and walls from one corner to the other, prying down every loose slab and switching to the Hydraulic Breaker for the stubborn ones. Smaller rigs ride on a compact articulated carrier for narrow-vein mines, while larger units carry a longer Scaling Boom for wide-heading metal mines and big civil tunnels. Some are built tracked instead of wheeled for very rough or steep ground. Across the range the purpose stays the same: take a person out from under the loose rock and put a steel pick there instead.