You may have used the machine in another job, but you cannot assume you can use it now without approval from your manager.
Forklifts and other machines can be very dangerous if used incorrectly by the user and those people around.
There is special training and maintenance needed for machines; do not attempt to do repairs on them unless you are qualified and approved by your employer.
If you are around where any mechanised lifting or moving aid is being used, keep it at a safe distance, wear the correct PPE and follow your workplace policies and procedures. If you have any doubts about any machine, ask your manager.