Komatsu PC290LC-6K Operation & Maintenance Manual page 115

Prohibited operations using dropping force of machine.
Do not use the dropping force of the machine for digging.
Digging rocky ground
It is better to excavate hard rocky ground after breaking it up by some
other means. This will not only reduce damage to the machine but make
for better economy.
Sudden lever shifting during HI-speed travel prohibited
Never carry out sudden lever shifting as this may cause sudden
starting.
Avoid sudden lever shifting from forward to reverse (or vice versa)
Avoid sudden lever shifting change such as sudden stopping from
near top speed (lever release operation).
12. OPERATION
2-71