Design and installation of variable geometry (4 × 4) dynamometers
Many chassis dynamometers intended for testing four, or more, wheel drive vehicles are designed so that the interaxle distance can be varied so as to accommodate a range of vehicles in a product family. The standard method adopted in 4 × 4 designs is for one, single-axle dynamometer module to be fixed within the building pit and the identical second module to be moved towards or away from the datum module on rails inside the pit. The range of interaxle distance for light duty vehicles (LDV) will be in the range of 2 to 3.5 m, but for commercial vehicle designs the range of movement will be far greater. This range of movement is important in that it tends to determine the design needed to accommodate that section of cell flooring that is required to move with the traversing set of rolls. In the LDV designs where the total module movement is around 1.5 m the moving plates can be based on a telescopic design with moving plates running over or under those fixed. Where the movement considerably exceeds 1.5m, then the moving floor designs may have to be based on a slatted sectional floor that runs down into the pit at either end, while being tensioned by counterweights or as part of a tensioned cable loop. All these designs can be problematic in operation and require good housekeeping and maintenance standards.
The traversing module is normally moved by two or more electrically powered lead screw mechanisms coupled to a linear position transducer so that a set position can be selected from the control room. For operational reasons, it is recommended that some positional indication, vehicle-specific or actual interaxle distance, is marked on the operating floor.
LDV units are usually traversed on flat machined surface rails having lubricated foot pads fitted with sweeper strips to prevent dirt entrainment; this is very similar to long established machine tool practice and has to be installed with a similar degree of accuracy. Large commercial vehicle rigs often use crane traversing technology rather than that of machine tools with crane rails installed on cast ledges within the pit wall design and the axle modules running within ‘crane beams’ running on wheels some of which are electrically powered.
Design and installation of variable geometry (4 × 4) dynamometers Many chassis dynamometers intended for testing four, or more, wheel drive vehicles are designed so that the interaxle distance can be varied so as to accommodate a range of vehicles in a product family. The standard method adopted in 4 × 4 designs is for one, single-axle dynamometer module to be fixed within the building pit and the identical second module to be moved towards or away from the datum module on rails inside the pit. The range of interaxle distance for light duty vehicles (LDV) will be in the range of 2 to 3.5 m, but for commercial vehicle designs the range of movement will be far greater. This range of movement is important in that it tends to determine the design needed to accommodate that section of cell flooring that is required to move with the traversing set of rolls. In the LDV designs where the total module movement is around 1.5 m the moving plates can be based on a telescopic design with moving plates running over or under those fixed. Where the movement considerably exceeds 1.5m, then the moving floor designs may have to be based on a slatted sectional floor that runs down into the pit at either end, while being tensioned by counterweights or as part of a tensioned cable loop. All these designs can be problematic in operation and require good housekeeping and maintenance standards. โดยปกติมีย้ายโมดู traversing โดยกลไกสกรูสองตัว หรือมากกว่าเป้าหมายขับเคลื่อนด้วยระบบไฟฟ้าที่ควบคู่กับพิกัดตำแหน่งเชิงเส้นเพื่อให้สามารถเลือกตำแหน่งที่ตั้งจากห้องควบคุม เหตุผลปฏิบัติ งานที่ บางบ่งชี้ตำแหน่ง รถ หรือตามจริง interaxle ระยะไว้บนพื้นปฏิบัติงาน ผ่านหน่วยจะไม่เหมือนกันมักจะแบน machined ผิวใหญ่มี lubricated แผ่นเท้าอาบกวาดแผ่นเพื่อป้องกันสิ่งสกปรก entrainment นี่คือคล้ายการฝึกเครื่องมือเครื่องจักรที่สร้างไว้นาน และได้มีการติดตั้งคล้ายคลึงกันของความถูกต้อง Rigs รถเชิงพาณิชย์ขนาดใหญ่มักจะใช้เครนข้ามสิ่งกีดขวางเทคโนโลยีแทนที่เครื่องมือพร้อมรางเครนที่ติดตั้งบน ledges หล่อภายในการออกแบบผนังหลุมและโมเพลาที่ใช้ภายใน 'เครนคาน' ที่ทำงานในบางแห่งมีไฟฟ้าขับเคลื่อนล้อ
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