About jacks and jack technology

Tools or machines that are able to lift heavy weight or press things apart with a heavy power and then hold the weight statically are generally called jacks. Usually a jack is very small compared with the power it can excert. Generally a jack is constructed in such a way that the heavy power is produced by a repetitive action of a smaller power. That smaller power can be muscular or electric .

Some jacks use a set of gears of various sizes coupled to each other so that each wheel drives a larger wheel around. Ultimately the largest wheel pushes along a tanned bar. There must also be a locking mechanism so that the whole meechanism does not run back again before so wanted.

The power in these jacks can derive from muscular circular actions or muscular pumping actions. The pumping action is usually derived from the use of a long handle giving a high power momentum. Such jacks can also be driven by an electric motor.

Other types of jacks use a cylinder with a piston into which one presses air or oil under high pressure. The high pressure is usually created in another cylinder with a piston used as a pump with repetive pumping actions. The pumping actions are usually done by muscle power using a long handle. There can also be gears between the handle and the piston pump that augments the power. There must be a valve that hinders backflow of the air or the fluid until so is wanted to relieve the pressure from the jack.

In still other jacks the upper part is pressed up by a mechanism that unfolds. The action of this mechanism is often excerted by a screw that goes through holes in the mechanism. The screw can be driven manually or by an electric motor.


About Compressor Technology - an overview

A compressor is basically a pump for air, other gasses, water or other liquids that excerts such a high pressure that the substance is pressed into a smaller volume in the outlet end. The volume reduction is great for gasses, smaller for liquids. If the compressor presses hard enough, a gas can possibly be compressed to a liquid state. The term "compressor" is of latin origin and means "together-presser".

The purposes of a compressor can be several. One can use compressors to press great amounts of a gas into a small volume so that it can be handled and transported practically. The pressure in such a gas will also drive the gas out of the container by own force, so that a pump will not be needed when the gas shall be used. A compressor can propell gas or liquids along with a high speed and hence high kinetic energy. The speedy substance can then be used to do several types of work. If the substance is projected in form of a thin ray, one can cut objects with it or clean objects for dirt. By letting the substance pass turbines it can drive machines of various kind. An example of such a turbine driven device is a dentist's drill.

The effect of a compressor depends upon the size of the internal mechanism, the volume of the inlet, the internal volume and the volume of the outlet. It also depends upon how fast the internal mechanism mooves. There are three basic compressor types in common use:

A piston compressor has one or several cylinders with pistons. The piston sucks the substance into the cylinder when it moves one way and presses it out by the opposite movement. Such a compressor also has valves in the inlet and outlet that hinder flow in wrong direction. Such a compressor has the advantage that it can exert high pressure even when it moves slowly.

A turbine compressor is basically one or more fans on a pivot inside a round holster. The inlet is situated in one side of the fan and the outlet at the other side. Such a compressor may or may not be equipped with valves. Such a compressor is effective only when run by high speed.

A centripetal compressor has a fan-like device on a pivot in a disc-like holster, but the blades of the fan stands horisontally on the pivot, not querely like in the turbine type. The inlet is at one side in the middle of the holster and there is one or several holes in the periphery of the holster serving as outlet. There may also be a round disc fixed to the fans at the opposite side of the inlet that makes the construction more robust and helps to avoid leaking of substance around the blades. When the pivot is moving around, the blades press the substance towards the periphery and out of the outlet. Also such a compressor may or may not have valves. Centripetal compressors also need high speed to be effective.

Whether such devices shall be called compressors or only pumps, depend upon the robustness of the construction and upon the power of the driving mechanism. The basic construction of pumps or compressors are the same.