초록 ▼

A device for measuring the coefficient of friction between a test surface and a test material, comprising a frame, a skid pad comprising the test material and attached to an underside of the frame to contact the test surface, a longitudinal force measuring device attached to the frame and having an

A device for measuring the coefficient of friction between a test surface and a test material, comprising a frame, a skid pad comprising the test material and attached to an underside of the frame to contact the test surface, a longitudinal force measuring device attached to the frame and having an axis, and a longitudinal pulling assembly exerting a longitudinal pulling force on the drag sled and the longitudinal force measuring device. The longitudinal force measuring device is capable of outputting data indicative of the longitudinal force applied to the device. The longitudinal pulling force is vertically aligned with the axis of the longitudinal force measuring device.

대표청구항 ▼

What is claimed is: 1. A drag device for measuring the coefficient of friction between a test surface and a test material, comprising: a frame; a skid pad comprising the test material and attached to an underside of the frame to contact the test surface; a system for adjusting the center of mass of

What is claimed is: 1. A drag device for measuring the coefficient of friction between a test surface and a test material, comprising: a frame; a skid pad comprising the test material and attached to an underside of the frame to contact the test surface; a system for adjusting the center of mass of the device; a longitudinal force measuring device attached to the frame and having an axis, the longitudinal force measuring device being capable of outputting data indicative of the longitudinal force applied to the drag device; and a longitudinal pulling assembly exerting a longitudinal pulling force on the drag device and the longitudinal force measuring device, wherein the longitudinal pulling force is vertically aligned with the axis of the longitudinal force measuring device. 2. The device of claim 1, wherein the center of mass of the drag device is vertically aligned with the axis of the longitudinal force measuring device. 3. The device of claim 1, wherein the skid pad test material comprises one of a rubber compound and polyurethane. 4. The device of claim 1, wherein the system for adjusting the center of mass of the device comprises uprights and a ballast weight. 5. The device of claim 4, wherein the system for adjusting the center of mass of the drag device further comprises a level attached thereto. 6. The device of claim 1, further comprising a stabilizer bar between the longitudinal force measuring device and the longitudinal pulling assembly. 7. The device of claim 6, wherein the longitudinal pulling assembly comprises a pull cable extending through a pulley, the pull cable being attached to the stabilizer bar such that the longitudinal pulling force is applied to the longitudinal force measuring device though the stabilizer bar. 8. The device of claim 1, further comprising an attachment system for attaching the skid pad to the underside of the frame, the attachment system comprising toggle clamps. 9. The device of claim 8, wherein the attachment system further comprises clamp bars extending between adjacent toggle clamps. 10. The device of claim 1, wherein the drag device is attached to a pull system. 11. The device of claim 10, wherein the pull system includes a winch and a tow cable. 12. A drag device for measuring the coefficient of friction between a test surface and a test material, comprising: a frame; a skid pad comprising the test material and attached to an underside of the frame to contact the test surface; a load cell attached to the frame and having an axis, the load cell being capable of outputting data indicative of the longitudinal force applied to the drag device; protection pins that protect the load cell from damage when the device is not in use; and a longitudinal pulling assembly exerting a longitudinal pulling force on the drag device and the load cell, wherein the longitudinal pulling force is vertically aligned with the axis of the load cell. 13. A method for measuring the coefficient of friction between a test surface and a test material, the method comprising: providing a friction measuring device including a skid pad comprising the test material and attached to an underside of a frame to contact the test surface, the friction measuring device also including a longitudinal force measuring device and a longitudinal pulling assembly attached to the longitudinal force measuring device; applying a longitudinal force with the pulling assembly to move the friction measuring device relative to the test surface, such that the load path of the longitudinal force is vertically aligned with a center of mass of the friction measuring device and an axis of the longitudinal force measuring device; and outputting data indicative of the longitudinal force applied to the friction measuring device, wherein the friction measuring device is used with a dynamic tire test machine, and the longitudinal force is applied to prevent movement of the friction measuring device relative to a test surface of the dynamic tire test machine, and wherein the test surface of the dynamic tire test machine is a sandpaper surface, and the friction measuring device is configured to determine when the sandpaper surface has become worn or inconsistent and should be replaced. 14. The method of claim 13, wherein the friction measuring device moves relative to the test surface at a speed to prevent slide sticking and keep the friction measuring device in a sliding mode to measure dynamic friction. 15. The method of claim 13, wherein the test surface is one of a proving ground, a race track, a roadway, and an airport runway, and the friction measuring device is pulled across the test surface to monitor one of a static friction and a dynamic friction. 16. A drag device for measuring the coefficient of friction between a test surface and a test material, comprising: a frame; a skid pad comprising the test material and attached to an underside of the frame to contact the test surface; a system for adjusting the center of mass of the drag device; a longitudinal force measuring device attached to the frame and having an axis, the longitudinal force measuring device being capable of outputting data indicative of the longitudinal force applied to the drag device; and a longitudinal pulling assembly exerting a longitudinal pulling force on the drag sled through the longitudinal force measuring device, wherein the longitudinal pulling force is horizontally aligned with the axis of the longitudinal force measuring device. 17. The device of claim 16, further comprising a stabilizer bar between the longitudinal force measuring device and the longitudinal pulling assembly, so that the longitudinal pulling force is transmitted to the longitudinal force measuring device through the stabilizer bar, the longitudinal pulling assembly being connected to the stabilizer bar so that the longitudinal pulling force is horizontally aligned with the axis of the of the longitudinal force measuring device.