Section 4
Crank & transmission — manual elevation
A simple single-stage gear is not enough: the required torque far exceeds sustained human capability without significant gear reduction.
Transmission ratio
i = T_output / T_input = N_output / N_input
The ratio equals the torque ratio, i.e. the gear teeth ratio.
| Sustained human force | 200 N (~20 kgf) |
| Crank arm | 0.25 m |
| Available human torque | 50 N·m |
| Required transmission ratio | ≈ 51:1 |
| Gear stages (8:1/stage) | 2 stages |
| Resulting rotation speed | 4.7 °/s |
| Time from 0° to 90° | ≈ 19 seconds |
A 2-stage gear train (e.g. 8:1 then 6.4:1) or a worm gear reducer (self-locking, safe, but slower) is needed. This is exactly why real tanks use motorized hydraulics instead of a hand crank.
Interactive transmission calculator
Crank & transmission
200 N
100 N400 N
0,25 m
0,1 m0,5 m
2 543 N·m
200 N·m5 000 N·m
40 tr/min
10 tr/min80 tr/min
Available human torque
50
N·m
Required ratio
50,9
: 1
Gear stages (8:1)
2
Time 0° → 90°
19,1
s
Elevation time (0→90°) by ratio — 40 tr/min
A single 1-stage gear is insufficient: a 2-stage train (e.g. 8:1 then 6.4:1) or a self-locking worm drive is needed.