What must be done BEFORE lowering the landing gear when uncoupling a semitrailer?

UNCOUPLING PROCEDURE must be done in the correct sequence to prevent injury and equipment damage. BEFORE LOWERING LANDING GEAR: Ensure the parking surface is solid and level — landing gear can sink into soft ground or asphalt in hot weather; soft ground can cause the trailer to tip when the tractor pulls away; position the tractor and trailer so the trailer will stand correctly after disconnection; set the trailer emergency brakes by pulling the trailer supply valve (the red knob); communicate with any loading dock personnel; THEN lower landing gear: Use the high gear on the landing gear crank to lower quickly; switch to low gear when contact with the ground is made to crank firmly; the landing gear should bear the trailer's weight before the fifth wheel is unlocked; LANDING GEAR HEIGHT: The gear should be cranked until the trailer is level and the weight transfers from the fifth wheel to the landing gear — the trailer will lift slightly off the fifth wheel plate when correct; verify the height is correct (trailer level, not nose-up or nose-down). THEN disconnect: Air lines and electrical connections; release fifth wheel locking mechanism; THEN pull tractor away slowly while monitoring that the trailer sits correctly on its gear. NEVER rush uncoupling — a trailer that falls or tips can injure workers, damage cargo, and damage the trailer.