Screw in the context of "Household hardware"

In physics and mechanics, torque is the rotational correspondent of linear force. It is also referred to as the moment of force, or simply the moment. The symbol for torque is typically ${\displaystyle {\boldsymbol {\tau }}}$, the lowercase Greek letter tau. When being referred to as moment of force, it is commonly denoted by M. Just as a linear force is a push or a pull applied to a body, a torque can be thought of as a twist applied to an object with respect to a chosen point; for example, driving a screw uses torque to force it into an object, which is applied by the screwdriver rotating around its axis to the drives on the head.

Torque is generally referred to using different vocabulary depending on geographical location and field of study, with torque generally being associated with physics and moment being associated with engineering. This article follows the definition used in US physics in its usage of the word torque.

A simple machine that exhibits mechanical advantage is called a mechanical advantage device - e.g.:

• Lever: The beam shown is in static equilibrium around the fulcrum. This is due to the moment created by vector force "A" counterclockwise (moment A*a) being in equilibrium with the moment created by vector force "B" clockwise (moment B*b). The relatively low vector force "B" is translated in a relatively high vector force "A". The force is thus increased in the ratio of the forces A : B, which is equal to the ratio of the distances to the fulcrum b : a. This ratio is called the mechanical advantage. This idealised situation does not take into account friction.
• Wheel and axle motion (e.g. screwdrivers, doorknobs): A wheel is essentially a lever with one arm the distance between the axle and the outer point of the wheel, and the other the radius of the axle. Typically this is a fairly large difference, leading to a proportionately large mechanical advantage. This allows even simple wheels with wooden axles running in wooden blocks to still turn freely, because their friction is overwhelmed by the rotational force of the wheel multiplied by the mechanical advantage.
• A block and tackle of multiple pulleys creates mechanical advantage, by having the flexible material looped over several pulleys in turn. Adding more loops and pulleys increases the mechanical advantage.
• Screw: A screw is essentially an inclined plane wrapped around a cylinder. The run over the rise of this inclined plane is the mechanical advantage of a screw.

Engineering tolerance is the permissible limit or limits of variation in:

1. a physical dimension;
2. a measured value or physical property of a material, manufactured object, system, or service;
3. other measured values (such as temperature, humidity, etc.);
4. in engineering and safety, a physical distance or space (tolerance), as in a truck (lorry), train or boat under a bridge as well as a train in a tunnel (see structure gauge and loading gauge);
5. in mechanical engineering, the space between a bolt and a nut or a hole, etc.

Dimensions, properties, or conditions may have some variation without significantly affecting functioning of systems, machines, structures, etc. A variation beyond the tolerance (for example, a temperature that is too hot or too cold) is said to be noncompliant, rejected, or exceeding the tolerance.

Machines include both fixed and moving parts. The moving parts have controlled and constrained motions.

The term excludes fluids that pass through the machine, such as fuel, coolant or hydraulic fluid, as well as mechanical parts (such as locks, switches, nuts, bolts, and screw caps for bottles) which are moved only to reconfigure the machine. A system with no moving parts is described as "solid state".

Wall studs are framing components in timber or steel-framed walls, that run between the top and bottom plates. It is a fundamental element in frame building. The majority of non-masonry buildings rely on wall studs, with wood being the most common and least-expensive material used for studs. Studs are positioned perpendicular to the wall they’re forming to give strength and create space for wires, pipes and insulation. Studs are sandwiched between two horizontal boards called top and bottom plates. These boards are nailed or screwed to the top and bottom ends of the studs, forming the complete wall frame. Studs are usually spaced 16 in. or 24 in. apart.

A bearing surface in mechanical engineering is the area of contact between two objects. It usually is used in reference to bolted joints and bearings, but can be applied to a wide variety of engineering applications. The choice of bearing surface depends on the application, load, speed, and operating conditions, and the design must be able to withstand high loads, resist wear and corrosion, and operate at high speeds.

On a screw, the bearing area loosely refers to the underside of the head. Strictly speaking, the bearing area refers to the area of the screw head that directly bears on the part being fastened.

A screwdriver is a tool, manual or powered, used for turning screws.

At a minimum, a screw drive is a set of shaped cavities and protrusions on the screw head that allows torque to be applied to it. Usually, it also involves a mating tool, such as a screwdriver, that is used to turn it. Some of the less-common drives are classified as being "tamper-resistant".

Most heads come in a range of sizes, typically distinguished by a number, such as "Phillips #00".

An explosive belt (also called suicide belt, suicide vest or bomb vest) is an improvised explosive device, a belt or a vest packed with explosives and armed with a detonator, worn by suicide bombers. Explosive belts are usually packed with ball bearings, nails, screws, bolts, and other objects that serve as shrapnel to maximize the number of casualties in the explosion.