the linch-pin of a wheel, to govern or control, the noise of a barrow
鎋 centers on a linch-pin that holds a wheel in place, which extends to the idea of governing or controlling something by keeping it secure. The noise of a barrow is a rare, specific application of the wheel-related sense.
鎋 combines 金 (metal) with 害, which likely contributes the sound and may relate to the idea of a pin or wedge. The exact historical development is uncertain.
The metal 金 on the left and 害 on the right suggest a metal pin that prevents harm by keeping the wheel from falling off. Picture a linch-pin as a metal guardian that controls the wheel's movement.
For カツ, imagine a metal pin that cuts through the axle to hold the wheel: cut -> カツ, and the pin governs the wheel's motion.