Abstract: A core lifter having a lifter bar assembly formed of an elongate lifter bar with a replaceable lifter bar extension coupling carrying a coupling ball pivotably, rotatably, and translationally coupled to a lifter base fixed to an ejector plate of a plastic injection molding apparatus, the bar extension coupling removably coupled to the bar by a coupling joint configured to automatically self-align the bar relative to the base and mold in which the bar extends in a direction generally orthogonal to a lengthwise extent of the bar. Bar extension coupling is formed of an extension link having one end carrying the ball and an opposite end slidably coupled to an end of the bar by coupling joint. A preferred extension link is of breakaway sacrificial construction and slidably attached to the bar via a coupling joint that is a floating dovetail joint.

Abstract: A locking device for preventing unauthorized retraction of a telescopic prop is made up of an adjustable clamp which can be fitted round the outer circumference of the prop together with a fastener for tightening the clamp, such as a nut and bolt with anti-tamper heads and a shield to prevent access to the head with a gripping instrument. The device can be placed around the outer circumference of an extended prop adjacent to the collar such that once the clamp is tightened the collar is sandwiched between the locking device and the pin. Alternatively the device can be placed around the outer circumference of the inner tube of the prop adjacent to and abutting the end of the outer tube of the prop in order to prevent unauthorized retraction of the prop.