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The operator is placed in the space above the sliding door. An electric motor, geared down to get a lower speed and a higher torque, drives a pulley at one end of a belt. The door is clamped to the belt. To open the door, the motor turns the pulley, which in turn turns the belt, which in turn drags the door. To close the door, the reverse occurs.
A rock-climbing technique where a leg is held in a position to maintain balance, rather than to support weight, often to prevent a barn-door. [2] There are three types of flagging: [12] [11] normal flag Flagging foot stays on the same side (e.g. flagging right foot to the right side of the body). [12] [11] reverse inside-flag
Shades of blue: standard door closer. Shades of red: opener gears. Gold: motor. Operators use various internal technologies. Some are built on top of a standard door closer. To open the door, the operator forces the closer in the opening direction. Then, the closer closes the door. The user may open the door manually, using just the door closer.
A door closer is a mechanical device that regulates the speed and action of a door’s swing. [1] Manual closers store the force used to open the door in some type of spring and reuse it to close the door. Automatic types use electricity to regulate door swing behavior. Door closers can be linked to a building's fire and security alarm systems. [2]
Principle of rope-shovel operation. [1]A power shovel, also known as a motor shovel, stripping shovel, front shovel, mining shovel or rope shovel, [2] is a bucket-equipped machine usually powered by steam, diesel fuel, gasoline or electricity and used for digging and loading earth or fragmented rock and for mineral extraction. [3]
The electric overhead garage door opener was invented by C.G. Johnson in 1926 in Hartford City, Indiana. [1] Electric Garage Door openers did not become popular until Era Meter Company of Chicago offered one after World War II where the overhead garage door could be opened via a key pad located on a post at the end of the driveway or a switch inside the garage.
The introduction in the later Middle Ages of siege cannons, which harnessed the explosive power of gunpowder to propel weighty stone or iron balls against fortified obstacles, spelled the end of battering rams and other traditional siege weapons. Smaller, hand-held versions of battering rams are still used today by law enforcement officers and ...
Diagram of a mid-ocean ridge showing ridge push near the mid-ocean ridge and the lack of ridge push after 90 Ma. Ridge push is the result of gravitational forces acting on the young, raised oceanic lithosphere around mid-ocean ridges, causing it to slide down the similarly raised but weaker asthenosphere and push on lithospheric material farther from the ridges.