Detailed Answer
Keys = number of actions + emergency stop + spares: Electric hoist (hoist/travel) = 6 keys; Overhead crane (hoist/trolley/gantry) = 8 keys; With aux. hook/clamp = 10 keys; Complex equipment (metallurgy/port) = 12 keys. Principle: better more than fewer (reserve for expansion), but don't waste (more keys = higher cost + more accidental presses). LDER LD-6SK to LD-12DK cover all scenarios; XINGJIA does too.
| 6 keys | Hoist |
| 8 keys | Overhead crane |
| 12 keys | Complex equipment |
Note:Verify the action count on site — don't guess from the nameplate.