A chainsaw guard for enhancing safe operation of a chain saw. The guard includes a housing providing a physical barrier that limits access to the cutter chain of the chain saw. The housing has an opening for exposing a selected portion of the cutter chain for cutting a target object such as the roof of a burning building or the exterior surface of a tree. A coupler adjustably connects the housing to the chain saw. To improve flexibility, the housing includes two sections that can move relative to each other. The housing alone or in cooperation with the object being cut succeeds in enclosing substantially all of the cutter chain at all times to prevent human injury by the cutter chain, and in keeping the cutting edge facing away from the user. The housing further reduces risk of injury by limiting the depth of the cut made by the chainsaw.

The invention is directed to a tensioning arrangement for a saw chain of a motor-driven chain saw. The saw chain runs on a guide bar mounted on the motor housing of the chain saw. The tensioning arrangement includes a rotatable disc having a spirally-shaped guide slot in which a lug of a slide piece engages. The longitudinal displacement of the guide bar is provided by rotating the disc. The guide slot in the disc extends over a rotational angle of at least 270.degree.. A still lesser slope of the guide slot is provided with a rotational angle in the range of 360.degree. to 450.degree.. The tensioning arrangement is especially suitable for adjusting the guide bar in motor-driven chain saws thereby adjusting the tension in the saw chain.

An apparatus for variable length belt splitting includes a stepwise feeder which urges the belt, such as conveyor belt, forward in discrete steps and a reciprocating cutter disposed downstream from the feeder. The feeder preferably includes both a holding clamp and a feed clamp that is connected to, and is moved with respect to, the holding clamp by a feed actuator. The cutter preferably moves parallel to the holding clamp and is moved back and forth by a bi-directional ram. The cutter splits the belt edge to edge at a predetermined depth in length increments corresponding to the feeder's step length to a total length determined by the user. Optionally, the feeder and cutter are connected to a support structure which allows the feeder and cutter to be placed at an angle with respect to the path of the belt through the machine, thereby allowing for diagonal splits to be made with respect to the longitudinal axis of the belt without stewing of the belt. Advantageously, some embodiments of the present invention allow for the belt to be split while maintaining the integrity of the reinforcing layers and the adhesion thereof to the main belt layers. The belt splitter allows for the belt to be split up to any distance selected by the user. A method for splitting belts includes feeding the belt to a cutter in discrete steps having a step length and moving the cutter in a reciprocating manner after each step. The movement of the cutter against the belt splits the belt from one side to the other in length increments corresponding to the step length to an overall split length determined by the user. Optionally, the split is aligned diagonally with respect to the longitudinal axis of the belt. The method preferably splits the belt without damaging any bonds between main layers and reinforcing layers and without damaging the reinforcing layers.