DualVee Single Edge Slide System - HEPCO - #19

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17 LA LR DualVee – Overview Load/Life Relationship Several factors influence the service life of a DualVee linear system. Through research and development a simple method has been devised to estimate the load/life relationship for a specific DualVee guide mechanism under defined loading conditions. The methodology accounts for the size of the DualVee bearing elements, relative spacing, and the orientation, location, and magnitude of the load. The curve is based upon clean, well lubricated track conditions, so for applications where lubrication is prohibited, a derating factor must be applied. It is important to note that secondary considerations such as maximum velocity, acceleration rates, duty cycle, stroke length, environmental conditions, the presence of shock and vibration, and extreme temperature ranges can all impact service life to varying degrees. As such, the sizing method outlined below should be used conservatively, and considered only as a guideline for the sizing of DualVee components and assemblies. When time and budget permits, the prototyping of a DualVee arrangement is recommended to confirm service life expectations. The Load/Life Equation — Sizing and Selection The life of a DualVee guide will be limited to the life of the most heavily loaded bearing in the design. Step 1: Calculate the resultant radial and axial loads reflected to each bearing element in the linear guide design. If assistance is required in resolving specific loads into the resultant reaction forces at the guide wheel interface, contact our applications engineering staff for support. It is recommended that the Application Data Sheet on page 19 be submitted beforehand, with as much application information detailed as possible. Step 2: Calculate the load factor for the most heavily loaded bearing. LF = LA / LAmax + LR / LRmax Where LF = Load Factor LA = Resultant axial load on the guide wheel LAmax = The maximum axial working load capacity of the guide wheel LR = Resultant radial load on the guide wheel LRmax = The maximum radial working load capacity of the guide wheel  Bearings should be sized such that LF 1  The most heavily loaded bearing will have the highest load factor Due to varying application load and speed parameters and environmental conditions, the appropriate adjustment factor must be applied to the maximum axial and radial working load capacities (LAmax and LRmax)as follows: Adjustment Application Factor Conditions 1.0-0.7 clean, low speed, low shock, low duty. 0.7-0.4 moderate contaminants, medium duty, medium shock, low to medium vibration, moderate speed. 0.4-0.1 heavy contamination, high acceleration, high speed, medium to high shock, high vibration, high duty cycle, dry running. Oscillating motion resulting in less than one full revolution of the wheel under load can cause accelerated wear on the internal bearing elements. Testing of such systems is recommended to verify compatibility of the design with load/life requirements. In lightly loaded applications bearing preload can be higher than the working load. A figure equivalent to 3% of the radial working load capacity should therefore be included in the LR figure when calculating life.