Patent ID: 8544536

Claim:
A coiled tubing injector, comprising: a plurality of chains, each of which is comprised of a continuous loop and carries a plurality of grippers; the plurality of chains being arranged for gripping tubing placed between the plurality of chains; the plurality of chains comprising at least two driven chains; and a drive system comprising, for each of the at least two driven chains, a drive motor for turning the driven chain to which the drive motor is coupled independently of the other driven chain, the drive system supplying power to each of the drive motors in parallel; wherein the drive system is adapted for reducing, in the event at least two of the at least two driven chains begin to turn at sufficiently different speeds indicative of at least one of the at least two driven chains slipping with respect to tubing placed between the plurality of chains, the difference in the speeds while continuing to supply power to each of the drive motors in parallel.