Abstract: A cutting tooth used on an endless chain-trenching machine to fracture and excavate the ground. The tooth includes a mounting portion for attachment to the chain and a cutting portion having a straight cutting edge at the leading end of the tooth positioned normal to the direction movement of the chain. The cutting portion is aligned from the mounting at an acute angle to the plane of the mounting portion and including convex surfaces on both sides of the cutting portion and a juncture line between the mounting portion and the cutting portion forms an acute angle with the direction movement of the chain whereby the cuttings produced by the tooth are lifted away by the chain as the chain is digging.

Abstract: A system for dispensing hazardous fluid particular suitable for gasoline service stations utilizing an electrical impact sensing switch mounted upon each dispenser wherein the contacts of the normally open switch close upon impact occurring at the dispenser and the switch controls a primary electrical circuit energizing the pumps providing pressurized fluid to the dispenser whereby impact forces de-energizes the pumps minimizing to actuate alarms and alert personnel of the impact.