An underfeed stoker advances fuel from a hopper into a retort with a reciprocating ram. Explore the forward-and-return motion, then estimate feed quantity and ram travel from an assumed mass per cycle.
Ram Feed and Travel Calculator
Enter an assumed mass per stroke, cycle rate, elapsed time and one-way ram stroke. The results estimate total feed and ram travel from those inputs; they do not establish boiler or combustion ratings.
Equation Used
- Entered mass per stroke is constant and supplied by the user.
- Every commanded cycle completes one forward and one return stroke.
- Slip, voids, compaction, fuel properties, combustion, air flow and thermal performance are excluded.
Each complete cycle includes one forward and one return stroke. The feed estimate assumes a constant delivered mass per cycle; actual fuel capture, compaction and combustion are not modeled.
Hopper, reciprocating ram and retort
Historical underfeed-stoker patents show fuel dropping from a hopper into a ram casing. A reciprocating ram advances successive charges through an inlet throat into a retort; some arrangements add independently driven pusher blocks farther along the retort.
The animation shows the hopper, feed ram and retort with a complete forward-return ram cycle.
Historical feed-motion illustration
Use the calculator to estimate feed and ram travel from cycle count and an assumed mass per stroke. It cannot select or operate a stoker, boiler, furnace, fuel, air system, grate or emissions-control system.
Cycle count and feed estimate
The factor of two in travel counts the forward and return ram motion. None of these identities predicts how much material a real stroke captures or delivers.
Accounting example
At an assumed 0.5 kg per stroke, 12 strokes per minute, 60 minutes and a 200 mm one-way stroke, the calculation gives 6.00 kg/min, 720 cycles, 360 kg and 288 m of total ram travel. These values follow from the entered assumptions; they are not operating targets.
Feed-estimate limits
Real stoker and boiler work requires equipment-specific documentation, fuel analysis, combustion engineering, controls, emissions requirements and qualified operation.
Stoker feed questions
Does this calculator predict fuel demand?
No. Mass per stroke is an input, not a prediction.
Does ram travel equal fuel advance?
No. It is actuator travel only.
Can these values size a boiler or air system?
No.
Primary historical references
- US2367799A, Stoker: hopper, ram casing, reciprocating feed ram, retort and secondary pusher blocks.
- US1620509A, Fuel-distributing means for underfeed stokers: hopper, ram casing, inlet throat and retort arrangement.
- US1035359A, Automatic stoker: successive fuel charges advanced into a retort by a reciprocating ram.
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