d) In the case of horizontal or upside-down operations (e.g. tunnels), once every hour the
operator should lower the hammer to a vertical position, so that any particles of rock
which have collected in the hammer can fall out. (Operator can alternate hammering
up and down.) If this is not done, the hammer impact will be wasted on the rock par-
ticles, and in addition will create thermal energy in the particles and hammer, causing
overheating. Prolonged overheating will cause the hammer materials to lose their
original mechanical resistance. In order to keep particles out of the hammer, an air
hose may be installed in the same way as would be done for underwater usage.