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A "4-way" (intermediate) switch is a purpose built double pole, double throw (DPDT) switch, internally wired in manufacture to reverse the connections between the input and output and having only four external terminals. This switch has two pairs of "traveler" terminals that it connects either straight through, or crossed over (transposed, or ...
A hand truck. A hand truck, also known as a hand trolley, dolly, stack truck, trundler, box cart, sack barrow, cart, sack truck, two wheeler, or bag barrow, is an L-shaped box-moving handcart with handles at one end, wheels at the base, with a small ledge to set objects on, flat against the floor when the hand truck is upright. [1]
Many variations on this theme have been created and marketed. "Touch-plate" devices can be operated by touching or merely waving a hand near the switch. Touch switches have no moving parts and electronically switch the light circuit. As of 1986 these remain specialty items. Electronic switches provide flexibility in terms of different ...
In 1949, Milwaukee Electric Tool Corporation added a spring clutch to handheld Milwaukee sanders, grinders, and circular saws, significantly reducing tool recoil. In the same year, Milwaukee Tool also introduced their 1/2" right-angle drill. This power tool allowed plumbers and electricians to drill holes in wood and steel. [7]
Each key of a computer keyboard, for example, is a normally-open "push-to-make" switch. A "push-to-break" (or normally-closed or NC) switch, on the other hand, breaks contact when the button is pressed and makes contact when it is released. An example of a push-to-break switch is a button used to release a door held closed by an electromagnet.
A latching switch is a switch that maintains its state after being activated. [1] A push-to-make, push-to-break switch would therefore be a latching switch – each time you actuate it, whichever state the switch is left in will persist until the switch is actuated again.
Pressing a button on the key unlocks all of the car doors. Another button locks the car. In 1980, Ford Motor Company introduced an external keypad-type keyless entry system, wherein the driver entered a numeric combination —either pre-programmed at the factory or one programmed by the owner— to unlock the car without the key.
A rotary switch is a switch operated by rotation. These are often chosen when more than 2 positions are needed, such as a three-speed fan or a CB radio with multiple frequencies of reception or "channels". A rotary switch consists of a spindle or "rotor" that has a contact arm or "spoke" which projects from its surface like a cam.