Rock Straight System: Hard Rock Longwall Mining System for Low Seam Deposits

Rock Straight System: Hard Rock Longwall Mining System for Low Seam Deposits

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The Cat® Rock Straight System is a fully mechanized longwall system adopted to hard rock conditions for continuous mining of low seam hard rock deposits. The Rock Straight System combines the use of a hard rock shearer (Hard Rock Miner HRM220), a hard rock chain conveyor (Hard Rock Conveyor HRC30) and hydraulic roof support (Hard Rock Roof Support HRS1220). It features the unique adaptation of Caterpillar “Activated Undercutting Technology” and has been specifically designed for the extraction of bedded hard rock deposits (e.g. platinum, copper, gold). The Rock Straight System provides economical cutting in the mining of thin seams and narrow veins, especially when selective mining of ore is required.

Hard Rock Miner HRM220

Miner – Typical Machine Length
22.3 ft

Hard Rock Conveyor HRC30

Conveyor System Length (approximate)
328 ft

Hard Rock Roof Support HRS1220

Roof Support – Height Extended
84.64 in


Total Installed Power (approximate)
938 hp
Miner Haulage Speed
0-6 m/min (0-19.7 ft/min)

Roof Support System

Support Resistance
320.38 psi
At height of 1600 mm (62.99 in) and setting load at 320 bar (4,641 psi).

Miner Machine Weight

Weight (total)
45.2 tons

Seam Height

Minimum to Maximum Cut
1.3 to 2.0 m (4.2 to 6.6 ft)

Conveyor System

Conveyor capacity (approximate)
176 tons/hr
100 m (328 ft) conveyor length/varies with rock density.

Dimensions (Approximate) – HRM220 Hard Rock Miner

Seam Range
1.3-2.0 m (4.2-6.6 ft)
Typical Machine Length
22.3 ft
Cutting Head Diameter
50 in
Installed Power Hydraulic System
73.7 hp
Cutting Units
Installed Power per Cutting Unit
177 hp
Installed Power Electrical System
427.6 hp
Cutting Depth (up to)
3.9 in
Cutting Drum Speed
60 rpm
Body Height
47.2 in
Machine Weight (approximate)
45.2 tons
Operating Voltage
1,000 V; 50 Hz; 3 AC

Dimensions (Approximate) – HRS1220 Hard Rock Roof Support

Height Closed
41.73 in
Height Extended
84.64 in
Canopy Width
62.99 in
Main Canopy Length
166.93 in
Swivel Canopy Length
59.05 in
Base Width
51.18 in
DA (double-acting) Ram Stroke
24.60 in
Leg Centers Distance (vertical to face)
1440/1660 mm (56.69 in/65.35 in)
Bearing Surface Base
38.061 ft2
Distance Roof Support Centers
69.29 in
Support Resistance (at height 1600 mm/62.99 in) – Setting Load at 320 bar (4,641 psi)
320.38 psi
Support Resistance (at height 1600 mm/62.99 in) – Yield load at 415 bar (6,019 psi)
376.95 psi
Support Resistance (at height 1600 mm/62.99 in) – Load at the end of swivel canopy
14.50 psi
10.25 tons
Canopy Extension Length
59.05 in

Dimensions (Approximate) – HRC30 Hard Rock Conveyor

Line Pan Length
102.95 in
Line Pan Height
11.02 in
Chain Length (up to)
328 ft
Line Pan Width
69.13 in
Apron Plate Spacing
4 × 108 mm (4 × 4.25 in)
Apron Plate Chain Diameter
30 mm × 108 mm (1.18 in × 4.25 in)
Chain Speed
2.3 ft/min
Capacity per Hour
176 tons