top-card

Century Dictionary and Cyclopedia

1. n. An indicator-card taken by a steam-engine indicator from the end of the cylinder above the piston, in Cornish pumping-engines operating with a beam. This was quite different from the card taken below the piston (or bottom-card), since the work of lifting the massive pump-rods was done on the lifting stroke, with steam pressure from the boiler on top of the piston. The bottom-card showed only the equalizing and the condenser pressures.
2. n. In a carding-machine, a top-flat.