A compound machine is nothing more than the union of two or more basic machines. The lever, wedge, and wheel are examples of basic machinery. Almost every tool we use on a daily basis is a compound machine.
A compound machine can be thought of as a single machine with multiple functions. For example, a screwdriver is a compound machine because it has both a driving and a driven function. Driving strings on a guitar are also composed of fibers that drive the body when strummed and drawn across the neck of the instrument. Sound is produced when these fibers are vibrated by the hand or a pick pen.
Basic machinery consists of two parts: a motor and an output device. The output device may be another motor, such as in the case of wheels and axles, or it may be something without power, such as a handle or lever. The input device is used to generate power from the engine or electric source and transmit this power to the output device. This input device can be as simple as a pedal for an automobile or as complex as a computer processor circuit board.
Simple machines are those that consist only of one type of basic machine. Examples include the pendulum clock, paper towel roll, and ballpoint pen. These devices have only a driving function.
Compound machines are simply machines composed of two or more basic machines. A wedge, an inclined plane (like a ramp), a screw, a pulley, a wheel and axle, and a lever are examples of simple machines. A jack is a machine that uses these three devices simultaneously to lift heavy objects. The term "compound" comes from the fact that many of these devices are used together to create something more complex than any of them alone.
Jack-up rigs are commonly used by oil companies to lift tanks off the ground so they can be repaired or replaced. The lifting mechanism consists of two jacks placed back to back with their heads up under the tank. Then another piece of equipment called a spreader bar is used to push down on the tops of the jacks. This forces the jacks upward, raising the tank off the ground. The whole process can be repeated as often as necessary.
Other common uses for jack-up rigs include lifting vehicles off the ground for repair or replacement of tires, engines, or other components; creating temporary storage spaces for use when shoreside facilities are limited; and lowering material into deep holes or trenches.
The first jack-up rig was built in 1947 by Olin Mathieson Chemical Corporation. It was designed to replace expensive and time-consuming hand digging of defense excavation sites.
A compound machine is one that is made up of more than one basic machine. Compound machines, like wheelbarrows or corkscrews, are made up of only two basic machines. Large compound machines, such as automobiles, are made up of hundreds or thousands of basic machines. Compound machines are easy to understand if you think about it: any combination of levers and wheels can be used to raise or lower something using the principle of leverage. For example, a lever can be used to lift something heavy by putting muscle power into it, while a wheel can be used to roll that thing back and forth. A wheelbarrow is just a lever with two wheels and a handle so you can transport something heavy from one place to another.
The word "machine" comes from the Latin for handwork, mensura, which means measurement. The first machines were human-powered devices used for measuring out grain for breadmaking or sand for glassmaking. As technology progressed, these human-powered machines were replaced with animal power, then steam power, and now electric power. But the concept of a machine remains the same: an object propelled by mechanical energy, such as a motor or windmill, that can be used to do work.
Wheelbarrows have been around for many centuries and are still in use today in some parts of the world.
Compound machines are made up of two or more basic machines that interact with one another to perform tasks. At other instances, it is straightforward to identify basic machines: a door, for example, contains hinges (which function as levers) and a door knob (a wheel-and-axle). However, a door handle consists of several parts that work together: the wheel, the axle, the spring, and the knob. None of these parts can be used by itself. Instead, they all must be put together to form a complete handle.
Door handles are simple examples of mechanical devices that consist of several components that work together to provide movement. Compound machines are useful because they can be designed so that only certain parts need to be replaced if they fail. For example, if the knob was the only part that wore out, it could be removed and replaced without having to replace the entire handle.
Mechanical devices such as door handles were first created around 1770. Before this time, people turned their doors knobs by hand which caused many injuries and deaths due to unsafe door hardware. The invention of the electric door knob in 1872 helped to reduce these hazards.
Handles have changed over time. Some modern door handles use magnetic locks instead of standard keys. This eliminates the risk of losing keys and provides increased security. Other features include illuminated door knobs for night visibility and single-touch auto-openers.