Abstract: Handles, extendable handles, and linkage mechanisms are examples of apparatuses that include a body; a pivotably attached head; cylinder, actuator, or hydraulic actuator; a fluid passage or hose; and a valve, blocking means, or hydraulic control device. The valve, blocking means, or hydraulic control device may be normally open and may close only when held closed, and may be connected on one side to the fluid passage or hose and on another side to atmosphere. An operator may use a tool, such as a drywall flat box attached to the head, by holding the handle and controlling pivoting of the head by operating the valve. Methods include providing for an operator to control a tool on a handle, and include providing the handle and instructing the operator to actuate the blocking means to hold the tool in a constant orientation relative to the handle.

Abstract: An extendable linkage mechanism for operating a slave actuator over a range of distances from a master actuator, an extendable handle for operating a tool over a range of handle length; and a tool for use by an operator for dispensing drywall joint compound into joints between sheets of drywall. Slanted engagement surfaces on master and slave wedges engage each other as well as master and slave rods to transmit motion and force at varying distances, for instance, from a lever at one end to a clamp at the other end. The elongated slave rod passes through orifices in the wedges. Structural or tubular members may slidably engage to provide extendibility.

Abstract: Drywall mud pump for pumping drywall joint compound, for instance, from a bucket into a drywall tool. The pump includes a cylinder, a piston, a rod, and a means, or a connection structure between the piston and the rod, for allowing the end of the rod to move laterally relative to the piston. Some embodiments have an elongated hole in the piston that receives a flattened or reduced diameter end of the rod, for example. Different embodiments include a pump head through which the rod passes, a handle, a linkage, a means for allowing the rod to pivot, a shortened guide, a means for preventing the piston from rotating about the rod, or a combination thereof. Pistons may include, for example, passageways with straight and curved sides, a flapper, an elongated washer to block the elongated hole, and a means for controlling the rotational position of the washer.

Abstract: A drywall finisher's flat box is disclosed, having an adjustable pressure plate spring, independent suspension for guide wheels on the back plate, and a wiper configured so that the pressure plate can be pushed flat against the back plate, thus expelling nearly all of the drywall compound from the flat box.