Force Sensing Load Pins

The load sensing clevis pin or bolt is another unique strain gage transducer developed by Strainsert (U.S Patent 3,695,096). It utilizes the internal strain gage process perfected by Strainsert during the last forty years and used so successfully in Strainsert Bolts and Flat Load Cells^®. The force sensing clevis pin offers percision force measurement by simply replacing any existing shear pins, clevis bolts, shear axles and many other types of pinned joints used in the Aerospace, Automotive, Military and Marine industries.

The internally gaged clevis pin is typically a double-shear arrangement with two shear planes as shown in the drawing below, however, cantilever load pins with a single shear plane are available.

SPECIFICATIONS (opens in pop-up window)

Specification Table and Drawing

Typically load P is applied at the center of the pin and the pin is supported at each end (P/2) by the Clevis. The strain gages are sealed inside small axial holes and are positioned at two locations at the clevis to clevis eye interfaces. In order to sense only those strains which are induced by the shear forces at these two sections, the gages are positioned and oriented with great precision, at a neutral plane relative to one specific direction of pin loading. The four strain gages (two at each location) are electrically connected to form a full bridge, the signal from each gage being additive so that the bridge output is proportional to the sum of the loads transmitted by the shear planes of the pin. The circuit typically includes temperature compensating, signal trim (optional) and balance resistors terminating in suitable connector socket or integral cable, and normally potted with a sealing compound inside the gage hole, for enhanced environmental protection.

If the force F is applied to the pin at other than the specified direction, the theoretical bridge output will be due to the component of the force along the sensitive direction, i.e. F cos X (Spec. Drawing Above). Therefore, typical pins incorporate an anti-rotation device for proper alignment, see Clevis Pin Installation for details.

The clevis pins or clevis bolts can be designed for extreme durability under even the most severe conditions temperature variations or working environments. These products have a wide range of applications, have a long operational life and are currently used on a variety of applications from simple force measurement solutions up to such cutting edge projects as the Mars Exploration Rover Mission for NASA, the Space Shuttle launching pad and hydrostatic or submersible vehicles deep under the ocean's surface.

Some Applications Include: