Keeping operating hours.

Gday all, first post from me.
We are starting a new earthmoving business and need to keep operating hours (as opposed to engine hours) for invoicing clients.
I’m trying to find the correct name for a ‘rocker clock’. I have searched the net to buy these things for the machines with no luck at all.
You put the round card in and the clock picks up the vibration and marks the card.
I used them a lot when I was operating about 10 years ago.
Maybe also called a wobble clock or job clock.
Can...

Keeping operating hours.

Keeping operating hours.