Abstract: A temperature sensitive motor control for use in roofing membrane welding devices is described. The control circuit gives an output impedance responsive to variations in the temperature of the welding device and ambient temperature. A thermocouple provides a voltage signal responsive to changes in the temperature of the heating plate of the welding device. An ambient temperature sensitive circuit element acts in conjunction with the input signal to provide an output signal that is responsive to both ambient temperature and heating plate temperature. The output signal is applied to a voltage variable impedance element which outputs an impedance that is a function of both application temperature and ambient temperature. In one preferred embodiment of the present invention, the ambient temperature sensitive circuit element is a thermistor. In an alternate preferred embodiment of the present invention, the ambient temperature sensitive circuit element is a diode-comparator circuit.

Abstract: An apparatus for cutting a roofing membrane is described. The apparatus includes a frame, means coupled to the frame for facilitating movement of the frame over a roofing membrane, a blade coupled to the frame for cutting the roofing membrane, and a guide member coupled to the frame for guiding the frame over the membrane. The guide member may include an edge guide and a bar coupling the edge guide to the frame. The edge guide is adapted to cooperate with an edge of the roofing membrane to move the frame along and parallel to the edge of the membrane. The guide member may be adjustable to permit the edge guide to be moved relative to the blade.