Abstract: A lock is provided for the slideout box of a travel trailer which consists of an extensible lead screw locking member which is placed on top the slideout box when in its inner position to apply a firm inward force keeping the box pressed inwardly of the trailer with consequent compression of the sealing gasket around the outer face of the slideout box.

Abstract: A self-propelled trailer maneuvering dolly for transporting a fifth wheel trailer or a travel trailer. The dolly has a frame, a front handlebar and castor for steering, a pair of rear drive wheels for driving the dolly, a pneumatic motor, and sprocket wheels and chains for transmitting power to the drive wheels. There is a pneumatically extensible and retractable vertical lift, which has a top for engaging with the coupling member of a fifth wheel trailer and it also has a hitch ball for hitching up to a convention travel trailer. A spring biased lift bracket below the frame keeps the drive wheels off the ground when the trailer is empty so that the operator can easily maneuver the dolly into position below the coupling member of a fifth wheel to be moved. A lever supplies pressurized air to the lift, which in turn raises the front end of the fifth wheel trailer. The weight of the trailer is centered on the dolly and also keeps the drive wheels on the ground.