A tape transport is the generic term for all parts of a magnetic tape

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

 player or recorder

Tape recorder

An audio tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape machine is an audio storage device that records and plays back sounds, including articulated voices, usually using magnetic tape, either wound on a reel or in a cassette, for storage...

 that the actual tape passes through. Transport parts include, but are not limited to, the head, capstan, pinch roller, tape pins, and tape guide. The tape transport as a whole is called the transport mechanism.

Capstan

The capstan is a rotating spindle used to move recording tape through the mechanism of a tape recorder

Tape recorder

An audio tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape machine is an audio storage device that records and plays back sounds, including articulated voices, usually using magnetic tape, either wound on a reel or in a cassette, for storage...

. The tape is threaded between the capstan and one or more rubber-covered wheels, called a pinch roller, which presses against the capstan, thus providing friction necessary for the capstan to pull the tape. The capstan is always placed downstream (in the direction of tape motion) from the tape heads. To maintain the required tension against the tape head

Tape head

A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa.-Principles of operation:...

s and other part of the tape transport, a small amount of drag is placed on the supply reel. Tape recorder capstans have a function similar to nautical capstans

Capstan (nautical)

A capstan is a vertical-axled rotating machine developed for use on sailing ships to apply force to ropes, cables, and hawsers. The principle is similar to that of the windlass, which has a horizontal axle.- History :...

, which however have no pinch rollers, the line simply being wound around them.

The use of a capstan allows the tape to run at a precise and constant speed. Capstans are precision-machined spindles, and polished very smooth: any out-of-roundness or imperfections can cause uneven motion and an audible effect called flutter. The alternative to capstan drive, simply driving the tape takeup reel (which was used on some cheap tape recorders), causes problems both with the speed difference between a full and empty reel and with speed variations as described.

Dual capstans, where one is on each side of the heads, are claimed to provide even smoother tape travel across the heads and result in less variance in the recorded/playback signal.

Pinch roller

The pinch roller is a rubberized free spinning wheel typically used to press magnetic tape

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

 against a capstan shaft in order to create friction necessary to drive the tape along the magnetic heads (erase, write, read).

Most magnetic tape recorder

Tape recorder

An audio tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape machine is an audio storage device that records and plays back sounds, including articulated voices, usually using magnetic tape, either wound on a reel or in a cassette, for storage...

s use one capstan motor and one pinch roller located after the magnetic heads

Tape head

A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa.-Principles of operation:...

 in the direction of the moving tape. However multiple pinch rollers may also be employed in association with one or more capstans. An example of the application of multiple pinch rollers is the Technics

Technics

Technics may refer to:* Technics turntables, no longer in production.* Technics , a brand name of the Panasonic Corporation* An anglicization of the Ancient Greek term techne, used primarily in media theory...

-RS1520 tape recorder which utilizes two pinch rollers located on the opposite sides of a single capstan shaft in order to provide a more stable transport across two sets of magnetic heads. Dual pinch rollers are also used (along with dual capstans) in auto reverse cassette decks to drive the tape in both directions as needed. In this case, only one pinch roller is pressed against its corresponding capstan at a time.

Tension arm

A tension arm is a device used in magnetic tape recorder

Tape recorder

An audio tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape machine is an audio storage device that records and plays back sounds, including articulated voices, usually using magnetic tape, either wound on a reel or in a cassette, for storage...

s/reproducers to control the tension of the magnetic tape

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

during machine operation. The recorders equipped with a tension arm can utilize more than one of them to control tape tension in different direction of winding or during different modes of tape operation. Tension arms can also be found on digital data recorders and other types of recorders/reproducers using continuous tape medium such as magnetic digital tape, perforated paper tape, analog magnetic tape etc.