There are two main types of industrial torque converters. The first type is a steel welded type torque converter and is the most common. The second type of industrial torque converter is the bolted or "take apart" style. The population of bolted style converters is declining. They are distinctly different from welded units, but the terminology is relatively the same. Identifying bolted torque converters requires some additional questions which are at the end of this section.

The following definitions are used to describe industrial torque converters:

• Identifying Marks – any numbers, letters, paint stripes, paint dots, etc. that are on the exterior of the converter body.
  
  
• Hub - the portion of the converter that is inserted into the pump and is located on the transmission side of the converter.
  
  
• Pilot - the portion of the converter that is inserted through the drive plate and into the flywheel and is located on the engine side of the converter.
  
  
• Splines – the machined grooves on gears, hubs and shafts.
  
  
• Stator Splines – the upper set of splines seen when looking down through the converter hub and into the center of the stator. Note: some specialized converters may have dual stators and therefore two sets of stator splines.
  
  
• Turbine Splines – the lower set of splines seen when looking down through the converter hub at the turbine assembly. Note: some converters also have another set of drive splines in the very bottom of the front cover that may drive a quill shaft for an auxiliary pump, etc.
  
  
• Mounting Style and Pattern – how the converter mounts to the drive plate.
  
  
• Shroud – sheet metal cover attached to the top of the converter body that acts as a heat sink and helps circulate more air flow to aid in cooling.
  
  
• Fins - metal ribbing on the exterior of the converter body that act as a heat sink and helps circulate more air flow to aid in cooling.
  
  
• Dowels – alignment pins on the mounting side of the converter that aid in drive plate alignment.
  
  
• Ring Gear – gear toothed metal ring welded to the outer edge of the converter.

Identify Vehicle and Remove Converter
When inquiring on industrial torque converters, you should first record the make and model of the equipment. Also note the type of transmission and engine, as well as the fuel type. The converter is easier to identify, and less likely you’ll make an identification error, if you remove it from the equipment. Be sure to remove the drive plate from the converter. Now you are ready to start identifying your torque converter.

Identify Converter Markings
The body of a welded converter is a one piece "non-serviceable" unit. If your torque converter is a welded unit, you need to search the exterior of the unit for any identifying marks, most notably on the engine side or "bottom" of the converter. Note any identifying marks you find.

Identify Hub Type
The next item you’ll need to describe is the type of hub. Here is the terminology for describing the hub style:

• Plain – smooth with no driving features of any kind.
  
  
• Eared – 2 or 4 small tabs or "ears" that stick out on the end of the hub.
  
  
• Flats - two flat areas machined into the sides of the hub.
  
  
• Slotted – small areas of material removed on the end of the hub.
  
  
• Geared – splined gear welded on to or machined into the hub. Count and note the number of splines or gear teeth.
  
  
• Flanged – flange located on the end of the hub.
  
  
• Grooved – groove machined into the hub to accept a snap ring or a sealing ring.

Identify Stator/Turbine Splines
Note how many stator and turbine splines. If you look down into the hub, the top set of gear splines are in the stator and the next lower set of gear splines are in the turbine. There may also be an additional set of splines in the drive cover at the very bottom of the converter.

Identify Mounting Style
Note the mounting style, bolt pattern, and pilot characteristics. The pilot is on the engine side of the converter. It will usually be solid, but sometimes they are hollow, flanged, center bored or stepped. Some converters have no pilots, instead, they use a removable input guide. Mounting styles and patterns can be described as:

• Mounting Nuts – threaded nuts (hex, round, rectangle, oblong, square, or triangle shaped) welded on the converter bottom. These nuts will be arranged in various patterns such as small circle, large circle, etc. that you’ll need to describe. Count the number of threaded nuts and identify the thread size and pitch. They can be U.S. standard or metric.
   
• Mounting Ring – a metal ring welded onto the bottom of the converter that has threaded holes in it. Count the number of threaded holes and identify the thread size and pitch. They can be U.S. standard or metric.
  
  
• Threaded Holes – individual threaded holes that are drilled and tapped directly into the bottom of the converter body. Count the number of threaded holes and identify the thread size and pitch. They can be U.S. standard or metric.
  
  
• Studs – threaded studs welded on the bottom of the converter. Count the number of studs and note the thread size.
  
  
• Straps – metal straps that are riveted to the bottom of the converter. These straps allow attachment directly to the flywheel (no drive plate used with this style).