Reference NumbersThe quickest way to determine which bearing you require is using the bearings reference number. Most bearings have their references numbers engraved on the bearings themselves, but these often rub off over time and so it may be necessary to measure the bearing yourself, as described below. |
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Measuring Bearings
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It is sometimes necessary to measure bearings to determine the correct bearing type. You can measure the dimensions of a bearing by using a vernier calliper like the one below or measuring accurately with a ruler. All bearings will have a width, an inner diameter and an outside diameter. Once you have determined the dimensions of your bearing, you can use our bearing search tool to find the correct bearing. There are three main types of bearing - roller bearings, ball bearings and needle bearings. The differences between these bearings are detailed below.
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Bearing Suffixes
Once you measured your bearing, you can use our search to find the correct bearing size.
e.g. Inside Diameter: 25mm; Outside Diameter: 52mm; Width: 15mm - Bearing Type: 6205
Once you know the bearing you need based on size, you can then choose further options:
The bearing also has a seal either side of the bearing and this will be indicated by the suffix:
ZZ or 2Z = 2 Metal Shields
2RS1 or 2RSR or DDU= 2 Rubber Seals
Additionally, bearings also have a clearance value. This provides the bearing room for expansion between the bearing races and will add a small amount of play between the two rings.
An example of where a larger clearance is required is if a bearing is likely to get hot. The heat needs room to escape otherwise there is a risk of bearing failure.
C2 = Clearance is less than international standard
No Markings = Standard Clearance
C3 = Clearance is greater than international standard
C4 = Clearance is greater than C3
Bearing Types
Ball Bearing - A ball bearing uses loose balls to maintain separation between the two races.
Roller Bearing - The same as a ball bearing but instead of balls, a roller is used to maintain the separation,
Needle Bearing - a small bearing which uses small rollers to reduce the friction between the races
Identifying V & Wedge Belts
- Any part number or brand on the belt?
- Cross section (top width x depth)?
- The inside length in mm?
- Plain wrapped profile or raw edge cogged (teeth)?
- Colour?
Identifying V & Wedge Belt Pulleys
- Any part number or brand on the pulley?
- What is the pulley diameter?
- Cross section (top width x depth of a V groove)?
- How many V grooves does the pulley have?
- If machined what is the bore and keyway size? Any grub screws?
- Or is the pulley taper bored for a use with a taper bush?
Identifying Poly-V Belts
- Any part number or brand on the belt?
- Cross section (top width x depth)?
- The inside length in mm?
- Number of V’s.
Identifying Poly-V Belt Pulleys
- Any part number or brand on the pulley?
- What is the pulley diameter?
- Cross section (top width x depth of a V groove)?
- How many V grooves does the pulley have?
- If machined what is the bore and keyway size? Any grub screws?
- Or is the pulley taper bored for a use with a taper bush?
Identifying Timing Belts
- Any part number or brand on the belt?
- Pitch of the belt (the distance between the centre of one tooth to the centre of next tooth)?
- The inside length in mm?
- The width of the belt?
- How many teeth on the belt?
- Colour?
Identifying Timing Belt Pulleys
- Any part number or brand on the pulley?
- Pitch of the belt (the distance between the centre of one tooth to the centre of the next tooth?
- How many teeth does the pulley have?
- What is the measurement between the pulley flanges?
- If machined what is the bore and keyway size? Any grub screws?
- Or is the pulley taper bored for a use with a taper bush?
The ways a Timing Belt can be Identified
- Many times the timing belt part number and the name of the timing belt manufacturer will be printed on the timing belt and will still be legible. While this is the ideal situation, there are many times when the timing belt part number is either incomplete, vague, or from a belt manufacturing company that is either out of business or has a timing belt numbering system that isn't easily cross referenced.
- If the timing belt isn't marked adequately, there are times when the timing pulleys are marked adequately to determine the pitch and profile of the timing belt. The pitch of the timing belt is the distance from the center of one tooth to the center of the next tooth. The problem is that there are several different tooth profiles or shapes for 3mm, 5mm, 8mm and 14mm pitches not easily discernible without proper tooling. These include the AT5/T5, PowerGrip HTD/ PowerGrip GT2, Powerhouse™, Powerhouse MX™, and Poly Chain profiles.
- If you can determine the exact pitch and tooth profile of the timing belt, you can narrow down your choices rather quickly by measuring the width of the timing belt and the overall length of the timing belt. Alternatively, you could count the teeth or cogs on the timing belt and multiply by the pitch to get the length of the timing belt.
- The unknown that remains is the material of the timing belts. Common timing belt materials include neoprene and polyurethane. Neoprene is a rubbery material that can flake after extended use and is typically black and fairly flexible. Polyurethane is typically slick and is a little more rigid, especially in larger sizes. Often times, polyurethane will be clear or white, but it can also be black.
- Once you have all of this information, the part number for the belt will look something like: 640-8MX-12
- The first set of numbers in most cases will indicate the pitch length of the belt. In this case, the pitch length is 640 mm. In MXL pitches, some companies use the first number as the pitch length but most companies indicate the number of teeth on the timing belt. At B&B Manufacturing, we decided to adopt the standard of the time, tooth count.
- The next set of characters, 8MX in this case, indicate the pitch and tooth profile of the timing belt. Common pitches and profiles include XL (.200"), L (.375"), MXL (.080"), H (.500") HTD (3mm, 5mm, and 8mm), Powerhouse™ (2mm, 3mm, 5mm, 8mm, and 14mm), T2.5, T5, T10, AT5, AT10, and Powerhouse MX™ (8mm and 14mm).
- The last set of numbers, 12 in this case, refer to the width of the belt. On metric sizes the number is how wide the timing belt is in millimeters. On standard sizes the number breaks down in inches with a leading zero for sizes under an inch such as: 012=0.125", 025=0.25", 037=0.375", 050=0.500", 075=0.75", 100=1.00", 150=1.50", 200=2.00", and 300=3.00"
- Often times at the end of the part number, there will be a letter to indicate from which material the belt is made. Common codes are: G for neoprene with fiberGlass reinforcements, UP for Urethane with Polyester reinforcements, US for Urethane with Steel reinforcements, and UK for Urethane with Kevlar reinforcements. In our example, the material code was not added because this timing belt is only offered in Urethane with Kevlar reinforcements.
Information required to identify roller chain
- Any part number or brand on the chain? i.e. 10B-1
- Pitch of the chain (the distance between the centre of one pin to the centre of the next pin)?
- The distance between the inside plates?
- The roller diameter?
- Single row (simplex) double row (duplex) or triple row (triplex) of chain strands?
- Surface finish/material?
Information required to identify roller chain sprockets and platewheels
- Any part number or brand identification? i.e. Challenge or 4SR12
- Pitch of the sprocket (the distance between the centre of one tooth to the centre of the next tooth)? i.e. 1/2"
- How many teeth does the sprocket have? i.e. 45
- Diameter of the sprocket or platewheel?
- Single row (simplex) double row (duplex) or triple (triplex) rows of teeth?
- If machined what is the bore and keyway size? Any grub screws?
- Or is the sprocket taper bored for use with a taper bush?