| 摘要 |
A tong assembly includes a case assembly and a tong head assembly disposed in the interior of the case assembly and adapted to engage a first sucker rod. A transmission assembly engaged to a hydraulic motor and including a backup tong assembly. The backup tong assembly includes a backup tong having a first end and an oppositely disposed second end adapted to hold a second sucker rod. A load pin engaged to the second end of the backup tong and an outer casing of the transmission assembly, the load pin includes strain gages for measuring a force applied to the first end of the backup tong to output a force signal. A rotary encoder engages a shaft of the hydraulic motor and outputs a position signal when a. A controller generates an output signal based on only one of the force signal or the position signal when the force signal is greater than a predetermined value or when the position signal is within a predetermined range of values. The output signal actuates a valve to direct fluid from the hydraulic motor to a hydraulic fluid reservoir. |
