Cycloidal drive

Cycloidal drive
Cycloidal drive thumb.gif

A cycloidal drive or cycloidal speed reducer is a mechanism for reducing the speed of an input shaft by a certain ratio. Cycloidal speed reducers are capable of high ratios in compact sizes. [1]

The input shaft drives an eccentric bearing that in turn drives the cycloidal disc in an eccentric, cycloidal motion. The perimeter of this disc is geared to a stationary ring gear and has a series of output shaft pins or rollers placed through the face of the disc. These output shaft pins directly drive the output shaft as the cycloidal disc rotates. The radial motion of the disc is not translated to the output shaft.


Theory of operation

Parts of a 10:1 cycloidal speed reducer mechanism

The input shaft is mounted eccentrically to the ball bearing, causing the cycloidal disc to move in a circle. The cycloidal disc will independently rotate around the bearing as it is pushed against the ring gear. This is similar to planetary gears, and the direction of rotation is opposite to that of the input shaft.

The number of pins on the ring gear is larger than the number of pins on the cycloidal disc. This causes the cycloidal disc to rotate around the bearing faster than the input shaft is moving it around, giving an overall rotation in the direction opposing the rotation of the input shaft.

The cycloidal disc has holes that are slightly larger than the output roller pins that go inside them. The output pins will move around in the holes to achieve steady rotation of the output shaft from the wobbling movement of the cycloidal disc.

The reduction rate of the cycloidal drive is obtained from the following formula, where P means the number of the ring gear pins and L is the number of pins on the cycloidal disc.

r = \frac{P - L}{L}

Single stage efficiency approaches 93% and double stage approaches 86%[2] with single stage reduction ratio up to 119:1 and double stage up to 7569:1 [3]


Unlike many other drive mechanisms, the input and output shafts of the cycloidal drive can not be reversed. This is because rotating the output pins will not rotate the cycloidal disc in the correct way.[citation needed]

Also, the eccentrically mounted cycloidal disk will cause vibration in the drive which will propagate through the drive/driven shafts. This will also cause increased wear on the exterior teeth of the cycloidal disk, as well as the interface with the output roller pins due to small relative motion caused by the vibrations. A second cycloidal disc installed a half-rotation relative to the first will balance the input shaft and reduce vibration.

See also


  1. ^
  2. ^
  3. ^

External links

Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Chain drive — Roller chain and sprocket Mack AC delivery truck at the Petersen Automotive Museum with chain drive visible Chain drive is a way of transmitting mecha …   Wikipedia

  • Propulseur cycloidal — Propulseur Voith Schneider Propulseur Voith Schneider …   Wikipédia en Français

  • Propulseur cycloïdal — Propulseur Voith Schneider Propulseur Voith Schneider …   Wikipédia en Français

  • Циклоидальная передача — или циклоидальный редуктор  это механизм, понижающий частоту вращения, и имеющий фиксированное передаточное отношение. Циклоидальные редукторы при своей компактности имеют большие передаточные отношения. [1] Ведущий вал приводит в движение… …   Википедия

  • Cycloid gear — The cycloidal gear profile is a form of toothed gear used in mechanical clocks. The gear tooth profile is based on the epicycloid and hypocycloid curves, which are the curves generated by a circle rolling around the outside and inside of another… …   Wikipedia

  • Gear — For the gear like device used to drive a roller chain, see Sprocket. This article is about mechanical gears. For other uses, see Gear (disambiguation). Two meshing gears transmitting rotational motion. Note that the smaller gear is rotating… …   Wikipedia

  • Voith Schneider Propeller — The Voith Schneider propeller (VSP), also known as a cycloidal drive (CD) is a specialized marine propulsion system (MPS). It is highly maneuverable, being able to change the direction of its thrust almost instantaneously. It is widely used on… …   Wikipedia

  • Differential (mechanical device) — For other uses, see Differential. A cutaway view of an automotive final drive unit which contains the differential Input …   Wikipedia

  • Propulsor Voith Schneider — Impulsor Voith Schneider El sistema de propulsión Voith Schneider (V S P , VS Propeller) por sus iniciales en inglés, también conocido como “ impulsor cicliodal ” (CD, Cycloidal drive) es un especializado sistema de propulsión marina. Es… …   Wikipedia Español

  • Transmission (mechanics) — Gearbox redirects here. For the video game developer, see Gearbox Software. 5 speed gearbox + reverse, the 1600 Volkswagen Golf (2009). A machine consists of a power source and a power transmission system, which provides controlled application of …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”