| 摘要 |
A vehicle 10 which inspects pipes 12 using flux-leakage has a flux generating electromagnet 14 and foils 18, 20 to transfer the flux to the pipewall 12. Sensors 22 detect flux forced to leak from the pipe by defects. The vehicle is required to pass 1-D bends as shown and has a swivel 40 having a load bar 48 on which there is a link 46 of a towing chain 26. On straight pipe the link 46 occupies a first position nearer to the axis 44. In a bend the swivel turns so that the link 46 can slide along the load bar 48 to a second position further from the axis 44. This reduces the angle which the chain 26 makes with the axis 44 and jamming of the vehicle 10 in the bend is avoided.
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