Abstract: A hydraulic jar for use in a well and a method of operating same in which an outer housing assembly extends around an inner mandrel assembly in a coaxial relation thereto to define two fluid chambers separated by a piston. The housing assembly is movable relative to the mandrel assembly to force the fluid from one of the chambers to the other. The fluid flow rate is varied between a relative low flow rate and a relative high flow rate in response to the relative position of the housing assembly causing corresponding movement at the latter assembly. A high impact load is transferred to a member connected to the jar in response to a movement at the relatively high flow rate. The jar can be used to create a high impact load in both an upward direction and a downward direction.

Abstract: A temperature-activated catalyst for polyurethane or liquid polymer cures comprising the catalyst supported on, e.g. mounted on or bound into, a polymer which is incompatible with, viz. insoluble in, the reacting polymer phase.The catalyst may contain organotin groupings and the polymer may be mobile or rubber and have a linear polymer backbone, e.g. styrene-allyl alcohol.The polymer may be glassy and be ground to a fine powder.