Shaft Sinking Jumbo

Overview

A shaft sinking jumbo is a suspended drilling platform used to bore the ring of blast holes at the bottom of a vertical shaft as it is excavated downward. Sinking a shaft is a cyclic operation: the crew drills a pattern of holes into the rock face at the shaft bottom, charges them with explosive, blasts, then mucks out the broken rock with a grab or clamshell before the cycle repeats. The jumbo carries out the drilling stage of that cycle. It hangs from winch ropes inside the shaft, lowers to a fixed standoff above the rock, and presents several rock drills to the face at once so a full round can be drilled in a fraction of the time a single handheld drill would take.

The machine is built as a Galloway Work Stage work stage carrying a ring of radial Radial Drill Boom arms, a Boom Indexing Slew Ring that turns those arms over the hole pattern, and the Hydraulic Power Pack that drives everything. Air, water and control services run down the shaft to the stage. Because the jumbo works inside a confined and wet bore with loose rock overhead, every subsystem is sized for that environment rather than adapted from surface equipment.

Suspended work stage

The Galloway Work Stage is the structural heart of the machine. It is a multi-deck platform whose outer Stage Ring Frame is matched to the shaft diameter, leaving a controlled clearance to the wall. Each Stage Deck Module is framed from Deck Cross Beam members and floored with Steel Floor Grating so water and cuttings drain through rather than pooling underfoot. The decks are stacked so that drilling, charging and service tasks happen on separate levels at the same time. Crews move between levels on the Inter-Deck Access Ladder, and every open edge carries a Handrail Stanchion and Toe Board because a dropped tool inside a shaft is a serious hazard to anyone working below.

How the booms work

The drilling work is done by the radial booms. Each Radial Drill Boom is a hydraulic arm built on a Boom Arm Weldment weldment, moved by a set of Boom Hydraulic Cylinder actuators that lift, swing and extend the arm so the operator can place a hole anywhere in its sector. At the end of the arm sits the Feed Shell, a guide beam that advances the drill into the rock under control of its Feed Cylinder and Feed Chain. The drill itself is a Hydraulic Rock Drill (Drifter), a hydraulic drifter that combines two motions: a Percussion Piston hammers the drill steel thousands of times a minute while a Rotation Hydraulic Motor turns it so a fresh edge meets the rock on each blow. The percussion energy passes through the Shank Adapter into the Drill Steel & Bit, a hollow rod tipped with a tungsten carbide Tungsten Carbide Drill Bit. A Diaphragm Accumulator smooths the pressure pulses so the percussion stroke stays even.

To cover the whole face, the booms are mounted on a Boom Indexing Slew Ring. Its Slewing Ring Bearing is a toothed turntable bearing driven by the Slew Drive Gearbox gearbox through a Slew Drive Pinion. Rotating the Boom Carrier Hub indexes the arms from one set of holes to the next without repositioning the whole stage, which keeps the drilled pattern accurate and the round on schedule.

Hydraulics, air and water

All boom and drill motion is hydraulic. The Hydraulic Power Pack holds two Axial Piston Pump axial piston pumps fed from a Hydraulic Reservoir reservoir, each turned by a Pump Drive Motor. Flow is distributed through a Valve Manifold Block whose Directional Control Valve spools route oil to each cylinder and motor, with a Pressure Relief Valve capping system pressure at 210 bar. A Oil Cooler and Return Line Filter keep the oil cool and clean despite the heat the drills add. Separately, the Air & Water Service supplies flushing: compressed air from the Compressed Air Manifold and water from the Flushing Water Manifold run through a Flushing Swivel into each hollow drill rod, blowing cuttings out of the hole and holding down dust. A Air Line Lubricator mists oil into the percussion air to keep the drifter internals alive.

Suspension and centering

The stage hangs on four Suspension Wire Rope lines terminated in forged Rope Socket fittings, each watched by a Rope Load Cell so the crew knows the load is shared evenly. Side stability comes from Shaft Guide Roller units that bear on the shaft wall, while four Centering Jack cylinders extend to lock the stage at a fixed standoff before drilling begins. Materials reflect the wet, abrasive duty: structural members are S355 steel, drill components run in the 17CrNiMo6 to 42CrMo4 range and are case-hardened or nitrided, and seals throughout use Oil Seal and O-Ring Set elements rated for high pressure.

Control and electrical

The crew runs the machine from the Operator Control Station, a post under a Falling-Object Canopy that meets ISO 3449 falling-object protection. A Control Console of Hydraulic Pilot Valve units and Control Joystick controls meters oil to the booms, with an LCD Panel showing pressures and rope loads. Power arrives from surface down a Trailing Power Cable into the Power Distribution Box, which feeds the pump motors, the ring of LED Work Light lamps and the Control PCB Module that supervises the safety interlocks.

Variants and use

Jumbos are sized to the shaft: a narrow ventilation shaft may carry four booms on two decks, while a large hoisting shaft over nine meters across uses eight booms on four decks. The drive can be all-hydraulic from a surface pack or use a stage-mounted electro-hydraulic unit. The defining job stays the same across sizes: drill a clean, accurately spaced round so the blast breaks rock to the planned profile and the shaft advances straight and on grade.