A metal working crank and slide press mechanism for reciprocating parallel members, for example, a carriage-mounted ram and a sleeve slidable on the ram. The press mechanism is arranged to resist heavy side pressure exerted upon the connecting rod which assumes extremely angular positions relatively to the carriage. A cross head and side thrust resisting levers produce a straight line motion by translating the thrust of the connecting rod into a direction in line with the travel of the ram-carrying carriage connected to the cross head. The carriage is mounted on wheels running on the top and bottom of hardened way strips, the wheels being adjustably mounted on eccentric axles to grip the ways with a predetermined amount of pre-load to prevent slack in the wheels. The working surfaces of the wheels and way strips extend radially with respect to the center of mass of the carriage assembly to minimize the effect of thermal expansion on the wheel pre-load.