I believe after thinking about it that your 933 is a track loader/ What vintage/model is it?
I mentioned pulling the throttle pedal up earlier (thought it was a rubber tired loader at the time), but the older Cat machines usually utilized some type of over center throttle shut off, be it on the pedal hand throttle or a seperate control. Short story, if it is an older machine it probably uses a manual control for shutdown!
Clark
PS Do you have the operator's manual by chance? I always suggest securing the proper literature for anything if possible!