One of the main assemblies utilized in overhead contact systems today is that of the cantilever. Cantilevers are double insulated rigid structures in which pipe, wire and fittings are constructed for securing and maintaining messenger and contact wire heights and locations. Cantilever systems are primarily used in curve applications where push-off or pull-off forces are critical. Light duty cantilevers are used where tangential situations are present. IMPulse offers an infinite variety of design options to meet the needs of cantilever systems. IMPulse provides time proven quality materials in conjunction with custom engineered cantilever systems. IMPulse provides typical light, medium and heavy arrangements utilized in single and double track systems. To determine the type of cantilever required for your application, you may use the charts and loading diagram. Once this is determined IMPulse cantilevers provide fittings which allow adaptability. This adaptability provides for system integration and adjustability.
Counterweight Tensioning Assemblies provided by IMPulse are used to maintain constant tension on the catenary wires during all normal operating temperatures. As the catenary wires expand or contract with changes in temperature, the weight moves up or down thereby maintaining a constant tension.
IMPulse NC LLC Counterweight Tensioning devices have a three to one mechanical ratio. This ratio reduces the amount of weight required to maintain the tension. Thus, the tension applied to the catenary is three times the weight of the counterweight. The catenary wires are terminated to the counterweight tensioning device using a proportional yoke plate. The yoke plate provides tension at a two to one ratio where the messenger wire tension is twice that of the contact wire.
IMPulse provides many types of counterweight assembly options from solid body counterweights to plate style. The plate style of weight is cast in segments with an interlocking feature maintaining weight stack alignment. The plate style also offers the versatility of adjustment should system requirements change. IMPulse counterweights provide for alternate methods of mounting such as inside pole, within beam and outside the pole. A counterweight is commonly cast of lead segment(s). However, other materials such as concrete may be specified.
IMPulse incorporates be specified various safety features into counterweight design. Counterweight systems, due to their weight capabilities, incorporate both high and low temperature stops. Low temperature stops are required to prevent system damage when temperatures fall below freezing. This feature is furnished to prevent excessive sag in messenger wire during heavy icing conditions. IMPulse also provides optional mechanical brakes which stop the counterweight should system tensions reduce too quickly, which is the case during catenary wire breaks.
Many factors are used to develop the Strain Insulators to meet specific needs. Existing structures, service requirements and aesthetic values are all considerations of the overhead contact system design. IMPulse Strain Insulators are made with high-quality fiberglass rod used to provide strength and electrical resistance required by the IMPulse Hi*Lite high-voltage insulators.
The end fittings provided represent the broad array of connection methods for IMPulse Strain Insulators. The eye and clevis ends are cast of quality ductile iron. The tapped ends are of cold-drawn steel. All fittings are hot-dipped galvanized, and swaged to the ends of the fiberglass rod. After assembly, the exposed fiberglass rod is coated with an alkyd paint for protection from UV damage and weathering.
Four end fitting combinations are commonly used to suit a variety of design needs. Included are two clevises in the same "In-Line" plane, two clevises at "Rotated" right angles, clevis and eye at "Rotated" right angles, and clevis and tapped ends. Other combinations are possible, depending on customer requirements.
IMPulse offers both 5/8-inch and 7/8-inch fiberglass rod insulators. The 7/8-inch fiberglass rod is recommended for use in proximity to frogs and crossovers. This application provides greater impact resistance to flying trolley poles. Both 5/8-inch and 7/8-inch fiberglass rod applications are 100% proof tested to their rated tension prior to product shipment.
IMPulse Strain Insulators can be furnished in virtually any length; however, the minimum recommended insulating length is five inches for system voltages up to 750 VDC contact systems.