Providing the Ultimate Solutions in Precision Displacement Sensors
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Providing the Ultimate Solutions in Precision Displacement Sensors
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Position Transducer Mounting, Displacement Cable Stretch |
Position Measurement & Control - Issue 29
POSITION TRANSDUCER MOUNTINGInstallation Options Galore Need some ideas on how to effectively mount your position transducers? Take a look at our Mounting Bases and Accessories or contact us. We have over 35 years of experience in solving challenging mounting problems. Example mounting bases include the h base and magnet base shown below were developed for automotive steering and factory inspection systems, respectively.
DISPLACEMENT CABLE STRETCHIs It Significant? Firstmark Controls position transducers generally use wire rope as the connecting mechanism between the application and the transducer. Two kinds of stretch occur in cable based on wire rope: constructional stretch and elastic stretch. This stretch is due to two different causes: 1. Constructional Stretch - When the cable is made, the load at the closing head is light. Therefore, there are small clearances between the wires and strands, and between the strand and the core. The application of initial load causes wires and strands to seat properly and a slight overall elongation of the strand or cable accompanies this section. The amount of constructional stretch is not constant for all cables - it depends on such variables as type of construction, length of lay, and other factors, including the load applied. 2. Elastic Stretch - Elastic stretch is the actual elongation of the wires of a strand or a cable. This is caused by the application of a load up to the yield point of the metal. The stretch is approximately proportional to the load applied. When the load is released, cable subjected to elastic stretch returns to its approximate original length, providing the stretch has not reached the yield point of the metal.  When the elimination of as much stretch as possible is important, the cables or assemblies can be proof loaded to remove most of the constructional stretch. For assemblies, this process also verifies the holding power of the terminals. Proof loading is usually done by applying a 60% load to the cable or assemblies. This load is based on the minimum breaking strength of the cable or fittings, whichever is lower. Handling the cable as little as possible after prestretching helps eliminate putting constructional stretch back in. For more details on cable stretch including its insignificant effect on position transducer accuracy, use the Displacement Cable Stretch Calculator. COMPANY BIRTHDAYCelebrating 35 Years Firstmark Controls celebrated its 35th birthday in June. The company was established in 1968 to design, develop, and manufacture pilot protection devices in support of space-based and high-performance test aircraft programs. In 1970, the company was awarded a NASA contract to produce precision, small-format position transducers for aircraft flight control testing. The successful completion of this contract led to the development and production of a complete line of position transducers. We look forward to helping you meet position measurement challenges in the next 35 years! Some Trivia from the Early Years
NEWS YOU CAN USE99.9% On-Time Shipping, One-Week or Less Lead TimeFirstmark Controls has always been committed to delivering products on schedule. In 2001, we began tracking our shipment performance. The result? In 2001, we shipped on time 97.9% of the time and in 2002, the figure was 99.3%. To date in 2003, we are at 99.9%. This shipment performance was achieved with customers spread over 40 countries and included both standard and custom products. We are also committed to shipping our standard position transducers one week or less after receipt of order. We can often ship the next or same day. 
ISSN 1527-5108 • Document Number S050O(NC) |
