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Modern manual door closer Eclipse door spring and separate checking mechanism. 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.
Platform screen doors at the Fuda Station, Tokyo, Japan, 2023. Platform screen doors (PSDs), also known as platform edge doors (PEDs), are used at some train, rapid transit and people mover stations to separate the platform from train tracks, as well as on some bus rapid transit, tram and light rail systems.
Utilizing a breaching tool is unnecessary if the door is unlocked and easy to open. [5] [3] [6] [1] If the door is locked, breachers can attempt to force inward-opening doors with a strong kick. The breacher will aim to hit the door near the locking mechanism, but not kick the doorknob itself as one can easily twist an ankle doing so. [7]
Manual hole drilling and spike or screw insertion and removal have been replaced by semi-automated or automated machines, which are driven electrically, by pneumatics, by hydraulics, or are powered by a two-stroke engine. Machines that remove spikes are called spike pullers. [32] [33] [34]
Pneumatic actuator operating a valve through a rack-and-pinion mechanism. [7] A pneumatic actuator is similar to a hydraulic one but uses a gas (usually air) instead of a liquid. [8] [9] Compared to hydraulic actuators, pneumatic ones are less complicated because they do not need pipes for the return and recycling of the working fluid. On the ...
A scissors mechanism uses linked, folding supports in a criss-cross 'X' pattern. [1] The scissor mechanism is a mechanical linkage system used to create vertical motion or extension. It consists of a series of interconnected, folding supports that resemble the shape of a pair of scissors, hence its name.
Tuning a control loop is the adjustment of its control parameters (proportional band/gain, integral gain/reset, derivative gain/rate) to the optimum values for the desired control response. Stability (no unbounded oscillation) is a basic requirement, but beyond that, different systems have different behavior, different applications have ...
Adjusting spring case. Also Centering spring cylinder. A cylindrical cast-iron holder in which an adjusting string is placed. [3] Adjusting spring seat A casting, or a part of the bolster of a two-wheel trailing truck, forming a bearing for the end of the adjusting spring. [3] Admission The opening of steam port to admit steam to one end of a ...