A tubing injector apparatus for use with variable diameter tubing. The apparatus comprises a pair of carriages which may be moved transversely and pivotally with respect to one another by actuating hydraulic actuator cylinders. A hydraulic control system uses relief valves to maintain a substantially constant pressure in the actuator cylinders when a tapered connector in the tubing passes between the carriages. A gripper chain in each carriage has gripper blocks to grippingly engage the tubing. A linear beam supports the gripper chain and has a plurality of resiliently biased segments therein to help maintain better contact with the tubing when the tapered connector passes through.