In sawing lumber, speed rather than power is necessary, so a direct-drive undershot wheel powered by swiftly running water provides that speed. A push rod, or pitman, connected to a crank on the right of the wheel moves a wooden frame or sash holding the saw blade up and down. A counterweight helps balance the weight of the blade and sash to produce smooth action. A smaller tub wheel in front can be engaged to return the log and carriage in preparation for another cut.