Ford New Holland, Inc.

William J Homik

David G Sokol

Roger W Sprague

A momentary electrical switch includes fixed contacts fixed relative to a switch housing and slidable contacts located within the housing. A contact operating mechanism includes a manual control knob, slide element and a support attached to the slide for supporting the slidable contacts, the contact operating mechanism being movable axially in a first direction against a compression spring when the knob is pulled. An interlock element extends beyond the periphery of the slide to engage the casing to prevent movement of the contact operating mechanism when the knob is pulled. A spring biased interlock release stem is moved axially in an opposing second direction by pressing on a pushbutton to disengage the interlock element from the casing. The movable switch contacts are moved in the first direction relative to the fixed contacts only by concurrently pressing in one direction on the pushbutton while pulling on the knob in the opposite direction. When the knob is released the compression spring returns the contact operating mechanism and the movable contacts to their neutral position. When the pushbutton is released the interlock element is again extended beyond the periphery of the slide. The switch has three positions and two sets of fixed contacts. In the neutral position one slidable contact bridges a first set of fixed contacts. When the knob is pulled in the first direction while releasing the interlock element, the slidable contacts bridge both sets of fixed contacts. In the second direction, neither set of fixed contacts is bridged.

Momentary electrical switch with mechanical interlock

A cold start control apparatus for diesel engines includes a cold start switch, engine temperature and speed sensors and a transistor all connected to a programmable controller. The transistor is connected in a series circuit with a cold start relay and the series circuit is connected to the run/crank positions of an ignition switch. The relay has a pair of contacts through which a battery voltage may be applied to a cold start assist apparatus provided for the engine. The cold start assist apparatus may be a thermostart element such as a glow plug ignitor, or a solenoid controlled ether injection system. A permanent memory in the controller stores an indication of the type of cold start assist apparatus provided for the engine. The controller senses for actuation of the cold start switch and applies a signal to the transistor thus turning it on if (1) the ignition key is in the run or crank position, (2) the engine is cold and (3) the cold start assist apparatus is a thermostart element. On the other hand if the cold start assist apparatus is an ether injection system, the controller responds to actuation of the cold start switch to apply a signal to the transistor only if (1) the engine is cold, (2) the ignition switch is in the crank position and (3) the engine speed is at least as great as a predetermined speed. While the transistor is on, voltage is applied to the cold start assist apparatus.

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Ephrata, PA, United States of America

William J Homik