| 摘要 |
PURPOSE:To obtain a device which makes it unnecessary to conduct fine adjustment for offsetting a direct-current offset part of a Hall element different for each device after a ball joint is assembled, by a method wherein the Hall element is driven by a pulse and an alternating-current output voltage thereof is amplified by an alternating-current amplifier. CONSTITUTION:A Hall element 9 sensing a magnetic force of a permanent magnet 8 is joined and fixed on the surface on the antiabrasion compensation bearing side of a closing plate 7. When a ball joint 1 surfers an abnormal abrasion, a head part 3 is moved relatively in the direction of a socket opening by the resilience of an abrasion compensation bearing 6. The magnet 8 recedes from the element 9 with this movement, a sensed density of a magnetic flux becomes small, an output voltage of the Hall element lowers, and the pulse amplitude of an output voltage of an alternating-current amplifier 13 lessens. Therefore, an output of a comparator 15 becomes zero, and a transmitter 16 transmits 17 only a carrier wave. This electric wave signal is received by a receiver, and a monitoring device provided for an operator displays that the joint 1 reaches the limit of abrasion.
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