A coal-cutting machine removes coal with a powered cutting head. This page illustrates the transverse picked drum of a continuous miner and calculates a simple feed relationship for one cutting line. Historical reciprocating and chain cutters use different mechanisms.
Coal-cutting Machine Interactive Calculator
Set drum speed, the number of successive picks on one cutting line, forward advance between those passes and pick-tip diameter. The calculator links rotational and translational motion; it does not predict coal breakage or cutting load.
Equation Used
- Uniform angular spacing on the illustrated cutting line.
- Steady feed and drum speed with no deformation.
- Diameter measured to pick tips.
- Illustrative input ranges, not machine ratings.
Uniform successive picks on one cutting line. Feed advance is not a universal chip-depth estimate. This schematic isolates drum kinematics; material fracture, power, cutting forces, dust and production tonnage are outside the model.
How the picked drum moves
A tracked chassis supports a cutter boom and a transverse rotating drum. Individual picks sit in holders around the head. A real drum distributes many picks across its width; the enlarged end view isolates one illustrative cutting line so successive passes are visible.
The green pick rotates with the head. In the lower view its center translates at the calculated feed speed while the pick rotates about that center. The resulting trace is its path in a stationary reference frame, not a prediction of a chip outline. Both motions use the same four-times slowdown. The lower trace repeats one revolution for inspection.
Komatsu’s 12CM literature shows the separate cutter, traction and gathering arrangements of a continuous miner. The drawing here is an explanatory schematic, not a dimensioned reconstruction or recommended machine setting.
References & further reading
Different coal-cutting arrangements
Continuous miners use a cutting head while advancing into the face. Longwall shearers move along the face with their own head and haulage arrangements. Older machines include chain cutters and reciprocating tools. Their detailed cutting geometries cannot be represented by one universal pick-engagement diagram.
This calculator is specifically a uniformly spaced, successive-pick model on one drum cutting line. It does not use the total pick count across the whole drum or the number simultaneously touching coal.
Feed per pick and per revolution
Let z be the number of successive picks on one cutting line, b the forward advance between successive passes in millimetres, n drum revolutions per minute, and D the pick-tip diameter in millimetres.
Feed = zbn / 1000 m/min. Pick passes on that line are zn per minute. Forward advance in one revolution is zb millimetres. Circumferential tip speed relative to the drum center is πDn / 60000 m/s.
The path of a selected pick is x(t) = v t + R cos(ωt), y(t) = R sin(ωt), with consistent units. Actual chip thickness depends on the pick path, lacing, spacing, engagement and prior cuts. It is not equal to the entered forward advance in every position.
Worked kinematic example
At 30 rpm, six successive picks on one cutting line and 15 mm forward advance between their passes give 180 passes/min, 90 mm/rev and 2.70 m/min feed. For a 1000 mm pick-tip diameter, circumferential speed is 1.57 m/s.
Doubling drum speed doubles both feed speed and tip speed. Doubling diameter changes tip speed and the trace curvature, but leaves feed unchanged when advance per pass, pick count and rpm stay fixed.
What these results mean
The outputs are geometric and kinematic quantities. They do not establish allowable haulage speed, motor power, pick force, dust generation or tonnes per hour. Those require the actual machine, material, cut dimensions and operating data.
Input ranges are illustrative. The drum view shows the selected number of successive picks on one cutting line. The lower trace combines the rotating tip radius with forward machine travel.
Coal-cutting calculator questions
Is pick count the total number on the drum?
No. It is the number of successive picks on one cutting line in one revolution. Total drum picks and simultaneous contacts are different quantities.
Is advance per pick the actual penetration depth?
No. It is the machine’s forward advance between successive passes. Chip depth and shape depend on the complete cutting geometry and material.
Why does changing diameter not change calculated feed?
Feed is set by advance per pass, passes per revolution and rpm in this model. Diameter changes circumferential tip speed and the pick trajectory.
Does the animation show a historical reciprocating cutter?
No. It illustrates a modern transverse rotary drum. Historical reciprocating and chain cutters require different motion models.
Separate actuator positioning tasks
A separate positioning task, such as moving an auxiliary linkage, needs its own stroke, linkage-angle and force calculation. The drum-feed calculator does not size an actuator or establish whether a product is suitable for mining equipment.
When comparing a cylinder to an electric actuator, convert the discussion into stroke, force, speed, duty cycle, and installed length. Matching one specification is not enough.
If the application needs synchronized motion, feedback should be treated as a requirement rather than an accessory. Two open-loop actuators wired together can drift apart when friction, load, or mounting geometry differs between sides.
- Map actuator stroke to the actual output travel before choosing a model.
- Check for binding, changing leverage, and peak load near the ends of travel.
- Decide whether timed motion is acceptable or position feedback is required.
For a FIRGELLI design review, calculate the load case with the FIRGELLI actuator force calculator and plan the switching or controller arrangement with the linear actuator wiring diagram generator. If an actuator or cylinder is already installed, the linear actuator replacement finder helps keep the comparison tied to real dimensions.
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