What is the definition of a "Pinion Gear"

[mgoblue]

I deal with solving problems with gear boxes containing 4-7 shafts and I often hear the word pinion shaft used. What information does this give me about a shaft? [sig]<p>Bob Sander<br><a href=mailto:robert.sander@solvay.com>robert.sander@solvay.com</a><br>[/sig]

 

[DonLeffingwellPE]

Main Entry: 3pinion
Function: noun
Etymology: French pignon, from Middle French peignon, from peigne
comb, from Latin pecten -- more at PECTINATE
Date: 1659
1 : a gear with a small number of teeth designed to mesh with a larger
wheel or rack
2 : the smaller of a pair or the smallest of a train of gear wheels [sig][/sig]

 

[Dan12]

Most gearboxes are speed reducers- high-speed, low-torque is input in order to get have a lower-speed, higher-torque output. When this is the case, the pinion is the gear at the input. It is typically the smallest gear in the geartrain (because it handles the least amount of torque). If the literature you are using refers to a &quot;pinion shaft&quot;, I would assume that this means that the gear teeth (the pinion teeth) are cut directly into a shaft which is then mounted to the gear case (as opposed to the gear being a separate item which is fastened to a shaft).

 

From my understanding gears always come in sets of 2 and &quot; pinion &quot; refers to the smaller in the set and &quot; gear &quot; to the larger. Pinion shaft would be the shaft the smaller one is attached to.

 

[MikeMech]

I have also seen the &quot;driving gear&quot; in a gear reducer referred to as the pinion, presumably because it is ususally also the smallest gear in the train.

 

[BrianDengel]

The pinion is the smaller of two gears in a gear set. When the gear (pinion) is made up of a small number of teeth (typically less than 14), it is usually manufactured as part of a shaft assembly. The reasoning for this is that a bore in a small gear cause it to be inclined to deform. If the pinion is intergral to the shaft, this deformation cannot occur. The only info that can be extracted from the gear being a pinion shaft is that the shaft diameter must be less than the root diameter.