Safety arrangement for a hand-held, power-driven portable tool

A safety arrangement for a power-driven portable tool such as a motor-driven chain saw or the like, the portable tool having a housing equipped with two handles both of which are grasped by the operator to hold and guide the tool during use thereof, one of the handles being a bail handle mounted at the forward part of the housing, the safety arrangement comprising:

• two switches associated with respective ones of said handles and operatively connected to the motor so as to cause the same to be operative only when both switches are closed;
• and
• the switch associated with said bail handle including:
• two contacts;
• at least one of said contacts being mounted with respect to said bail handle so as to be displaceable from a first position whereat said bail handle switch is open to a second position whereat said contacts come into mutual contact and said bail handle switch is closed;
• and elastic means for acting on said one contact to effect said displacement to said second position in response to pressure applied to said elastic means by the operator of the tool when grasping the bail handle.

A motor-driven portable tool such as a chain saw or the like comprising:

• a housing having two handles attached thereto which are grasped by the operator to hold and guide the tool during use thereof;
• a gasoline motor mounted in the housing;
• a working tool for performing the work of the portable tool;
• speed-dependent mechanical coupling means for coupling said working tool to said motor when the rotational speed of the latter increases beyond a predetermined value thereof and for decoupling said working tool from said motor when the rotational speed of the latter falls below said predetermined value thereby disabling said working tool so as not to constitute a danger to the operator;
• an electronic control device operatively connected to said motor for maintaining the speed thereof below said predetermined speed when said device is activated;
• a safety switch associated with one of said handles said safety switch being actuable from an open position to a closed position in response to pressure applied thereto by the operator of the tool when grasping said one handle;
• and,
• said electronic control device including control circuit means incorporating said safety switch for maintaining said device in the deactivated condition so long as said safety switch remains in said closed position.

A motor-driven portable tool such as a chain saw or the like comprising:

• a housing having two handles attached thereto which are grasped by the operator to hold and guide the tool during use thereof, one of the handles being a forward handle mounted at the forward part of the housing;
• an electric motor mounted in the housing;
• an electric supply circuit for supplying current to said motor;
• a working tool operatively connected to the motor;
• a safety arrangement including two switches associated with respective ones of said handles and forming part of said circuit;
• the one switch associated with said forward handle including first and second contacts, at least a portion of one of said contacts being displaceable from a first position whereat said one switch is open to a second position whereat said contacts come into mutual contact and said one switch is closed;
• and, elastic means for acting on said one contact to effect said displacement to said second position in response to pressure applied to said elastic means by the operator of the tool when grasping the forward handle;
• and,
• electronic switch means for controlling the flow of supply current to said motor;
• said electronic switch means including:
• an electronic switch serially connected into said supply circuit and having a control circuit;
• and said forward handle switch being connected into said control circuit for switching said electronic switch into its conductive mode when said one contact is in said second position;
• and,
• a logic circuit connected into said control circuit for activating said electronic switch means when said one contact is in said second position.