| 摘要 |
A mobile service rig for servicing an oil well includes a variable speed engine and a multi-speed transmission that selectively powers a drive wheel for transport, a hoist for lifting and lowering well-related components, and a hydraulic circuit for a tong used in tightening and loosening sucker rods or tubing. A speed adjuster operatively coupled to the engine limits the speed of the engine when the tong is operating, while a flow restriction limits the rate of hydraulic fluid flowing through the tong. Such an arrangement reduces power consumption, reduces heat, and avoids over tightening a sucker rod connection.
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