Industry Fun Facts

Be the smartest guy at the water cooler.

Ask Frankie
A Fun Fact!

Type a keyword into the box below.
Example: "bearing"

Can you tell the I.D. of a Bearing by the part number?
Frank, in many cases, yes. For example, if you take the last two numbers of a metric bearing part # starting with the "04" size and up, multiply by 5
Example: 62"04" x 5 = 20 mm I.D.

Other examples:
   72"05" x 5 = 25 mm I.D.
   53"06" x 5 = 30 mm I.D.
   13"07" x 5 = 35 mm I.D.
   222"08" x 5 = 40 mm I.D.
   64"10" x 5 = 50 mm I.D.

Memorize the first 4 sizes and you can be the smartest guy around the water cooler!
   6200 = 10 mm
   6201 = 12 mm
   6202 = 15 mm
   6203 = 17 mm
Do Taper Lock Bushing part numbers mean anything? For example 2517 x 1 1/2
Yes, it goes as follows:

What is the difference between and "SD" and an "SDS" Q.D. Bushing?
Frankie, good question! The difference between the two is that an "SDS" is nothing more than a short "SD". i.e.: length thru the bore. In a pinch, you can substitute one for the other. Example: SD x 1" and SDS x 1"
What does Q.D. Bushing stand for?
Frank, Q.D. means Quick Detachable
Someone told me that it is wrong to use Anti-Seez compounds on Q.D. Bushings. True or False?
Frankie, that is an absolute truth. Never use Anti-Seez on Split Tapered Bushings.
Is it possible to tell the length and top width of a v-belt by its part#?
Frank, as a matter of fact it is. In the Fractional Horsepower (FHP) and the High Capacity
    (Hi-Caps) series, it goes as follows:
    Examples: F.H.P. (3L, 4L, 5L)
    Picture this:

Hi-Caps go much the same way. Example: 3V, 5V, 8V, or 3VX, 5VX, 8VX
How can you tell top width and length on A, B, C, D & E V-Belts?
There is a bit of memorization, but it can be done. It goes like this:
A = 12" T.W.      }
B = 58" T.W.      }
C = 78" T.W.      }    Memorize
D = 1 14" T.W.   }
E = 1 12" T.W.   }
A, B, C, D & E as it relates to the part # are measured on the Inside Circumference (I.C.)
B60 = 58 T.W. and 60" I.C.
C60 = 78 T.W. and 60" I.C.

To get O.C., memorize the following:
A - 60 + 2" = 12" T.W. x 62" O.C.
B - 70 + 3" = 58" T.W. x 73" O.C.
C - 100 + 4"= 78" T.W. x 104" O.C.
D - 210 + 5"= 1 14" T.W. x 215" O.C.
E - 144 + 6" = 1 12" T.W. x 150" O.C.
How about the variable speed belt part numbers?
Frankie, that's a simple one.
    Example: 1422V480
Do A.N.S.I. standard roller chain part numbers stand for anything?
Why yes, they do. Listed below are standard roller chain part #'s
25, 35, 41, 40, 50, 60, 80, 100, 120, 140, 160, 180, 200, 240

Simply take the first # in the case of a two digit part#, or the first two #s in the case of a 3 digit part #, put it over 8 and it will provide you with the pitch or pin to pin measurement.
= 12"
= 1"
= 3"

The above is a rule of thumb and does not tell all.
Example: Heavy Chain
Extended Pitch
What does ANSI stand for?
American National Standards Institute
Can a shaft size be determined by looking at a C/R oil seal part #?
Absolutely! For example: 17284 C/R would have a nominal shaft size of 1.7" derived from the first two digits.
What does NEMA mean?
National Electrical Manufacturers Association
Do NEMA motor numbers mean anything?
Good question! Take, for example #365T. Divide the first two numbers on a three digit part # by 4 and it will provide the shaft height of the motor in inches. 365T has a motor height of 9", 36 ÷ 4 = 9
What does A.G.M.A. stand for?
Frankie, that would be American Gear Manufacturing Association
When they say A.B.E.C. 3, 5, 7, 9, what does that mean?
Annular Bearing Engineering Committee, which dictates as to the quality of the precision of class 3, 5, 7, 9; 9 being the top quality of a given bearing.
On a worm drive, which is the worm and which is the worm wheel?
The worm is the gear that looks like a screw, and the worm wheel mates @ 90º to it
A Timing Belt number of, for example 700H150 means what?
So, what does XL, L, H, XH, XXH tell us about timing belts?
XL (extra light) = 15" pitch
L (light) = 38" pitch
H (heavy) = 12" pitch
XH (extra heavy) = 78" pitch
XXH (extra extra heavy = 1 14" pitch
Can you tell the outside diameter of a sheave by the part #?
Yes and no. If the part # is that of a Hi-Cap type as in 3V, 5V & 8V belts, yes.

No, if the part # is that of a conventional type belt as in A, B, C, D, E. Unless you memorize a few numbers...
On a worm gear drive, which gear is steel vs. bronze?
The worm is always steel and the worm wheel is bronze.
I see F.H.P. on some belts. What does it stand for?
Well Frankie, that is a designation for Fractional Horse Power.
Those belts are designed for below 1 H.P.
Example: 12 H.P., 34 H.P., 13 H.P., etc.
Why do some V-belts have cogs on the inside?
Great question! Contrary to popular belief, it is not for grip. They are designed for heat dissipation and minimal pulley wrap or the ability to go around a smaller pulley than the same belt without cogs. Think of it as your finger when you straighten then close.
Who knows what P.D. stands for?
Francis, P.D. means Pitch Diameter on a sheave.
For example: Pitch Diameter is actually a little less than O.D. or Outside Diameter. Pitch Diameter is roughly where the center of the v-belt comes in contact with the sheave groove. (This is a close approximation)
Do timing belts go by any other names?
Why, yes they do. Timing belts are also referred to as positive drive belts because they have positive engagement, i.e. teeth to teeth like chain and sprockets. Another fancy name would be synchronous drive belts because they don't slip like v-belts and they allow for a synchronized drive.

Example: A printing application where print needs to repeat and not wander down the page.
I recently put a set of 4 B-90 v-belts on a sheave and lined up all the part numbers. In other words, B-90/B-90/B-90/B-90 straight across. I tensioned them as prescribed, turned the drive on and then turned it off. I was shocked to see that the labels no longer lined up. Why?
Excellent question! Simple answer: v-belts are designed to slip a little on startup so as not to break by attempting to transmit all the horsepower all at once.
What is Double Pitch Roller Chain?
Double pitch roller chain has a pitch twice that of corresponding ANSI single-pitch chain.

Example: Double pitch roller chain #.
Drive Series - add 2000 to the base ANSI standard number.
(e.g. 2050 = base number 50 or 5/8" pitch x 2 = 10/8 or 1 1/4" pitch)
When they say Drive Series vs/ Conveyor Series in roller chain, what is the difference?
As a general rule:

Drive series has an hour glass side plate

Conveyor series has a straight side plate
Frankie should know this, but is a little confused by the word "Pitch".
Pitch is talked about in different products. What does "Pitch" mean?
Generally speaking, "Pitch" means the center of one thing to the center of the next.
Example: Roller Chain
#40 Roller Chain is 1/2" pitch
From the center of one pin to the center of the next pin.

More Examples:

Timing Belts = center of one tooth to the center of the next tooth.

HTD Belts = center of one tooth to the center of the next tooth.

NOTE: Not to confused with 'Pitch Line'
What is the difference between a Miter Gear and a Bevel Gear?
They look very similar to me, Frankie.
Frankie says they look similar because they basically are. The main difference is that a Miter Gear is a one to one drive at 90°, whereas a Bevel Gear is also a 90° drive but comes in various ratios

Example: 2:1, 10 tooth and 20 tooth

Miter Gear
Miter Gear
Bevel Gear
Bevel Gear

Frankie, do Spur Gear numbers mean anything?
Yep, Example: S824 breaks down as follows:
gear ratios
spur gear
Spur Gear
Frankie, I hear the term Pressure Angle from time to time when talking about gears.
What does that indicate?
I will give the short answer by using a simple gear. A straight tooth, or spur cut, which is a parallel drive, comes in two basic pressure angles (P.A.) 14 ½° and 20°. It is nothing more than the angle at which the teeth are cut. You need a gear gauge to tell one from the other.
Frankie, can you help with a simple dispute that we have in our maintenance shop? How many shaft heights does your standard cast iron ball bearing pillow block come in?
A short answer would be 3. Low, normal and high.
Pillow Block
What dimensions are critical in identifying a pillow block?
Great Question. Base to center of shaft, center to center of bolt holes and shaft diameter.
Pillow Block
Frankie, what does H.T.D. stand for?
Simple! “High Torque Drive”. They are the rounded tooth profile belts that look like timing belts.
When looking at an electric motor name plate, what does T.E.F.C. mean?
Frankie knows. “Totally Enclosed Fan Cooled”. That is the type of enclosure the motor is made with. Others are T.E.N.V. (Totally Enclosed Non-Ventilating) and O.D.P. (Open Drip Proof)
Frankie, one of the guys at the water cooler said that the belts with the grooves that run with the length of the belt are called Serpentine Belts. Is that true?
Yes, although that is slang for the proper name of “Poly-Vee Belts”. They call them Serpentine because when used in the automotive world, they snake back and forth through pulleys.
Poly Vee-Belt
What is a Spherical Roller Bearing vs. a Cylindrical Roller Bearing, vs. a Taper Roller Bearing?
Frankie can help with this. See photos below for an example of what a roller from each would look like.
Spherical Roller
Cylindrical Roller
Taper Roller
Frankie, can you run a gear with a 14½° P.A. with a gear with a 20° P.A.?
Absolutely not! First of all, P.A. stands for Pressure Angle, or the angle at which the teeth are cut. a 20° and a 14½° won’t mesh properly.
Frankie, on standard cast iron mounted units, what are common locking mechanisms, bearing to shaft?
There are numerous. And my observation is that it is, in many cases but not all, a personal choice as to which one you use. Common are Eccentric, Concentric, Set Screw Inner Ring, Skwezloc.
Eccentric Locking
Concentric Locking
Set Screw Locking
Skwezloc Locking
I have one for Frankie Fun Fact. What is a take up bearing used for? One of the guys in the shop said it is an adjustable bearing.
Wrong, it is not an adjustable bearing. They are designed to ride in a take-up frame and take up slack or stretch that occurs over time in chain, belting, or other conveyor components.
Take-Up Banner
Can Frankie give us a rule of thumb as to what is a safe operating temperature for a Bearing?
Sure, and you might think it to be hot, but none the less, a safe number would be 180° F.
Frank, is there any rhyme or reason to a part # that I might see on a sprocket?
Absolutely! For example: 40BS20 x 1”
Frankie, is there a simple formula that you could give us to help figure out RPM’s on a v-belt drive?
Yes sir, do as I illustrate and you will find it to be fairly easy. Make the following drawing and fill in the blanks.

Step#1. 6 ÷ 3 = 2 or 2:1 Speed Ratio
Step #2. 1750 Motor RPM ÷ 2 (Speed Ratio) = 875 RPM
Above example 875 RPM (Normal step down drive)
Is there a formula that Frankie has that helps with figuring out v-belt length?
Yep, but I need you to make a drawing first. (Example below)
Ok Frankie, is there a safe rule to follow as to where you place an Expansion Block vs. the Non-Expansion Block in a Drive?
Simple answer would be to always place the Expansion Block farthest away from the actual driver “Motor”.
At times I see a letter followed by a # on the outer ring of a bearing. Ex: C3
Does that have any significance?
Yes, it does for sure. It speaks to the internal running clearance in a bearing or the clearance between balls or rollers and raceways. Ex: C1, C2, C3, C4, C5
Frankie, why are mounted units, Ex: Pillow Blocks, 4 Bolt Flanges, etc. self-aligning?
The self-aligning feature in mounted units is there to compensate for imperfections in mounting planes.
Ex: Shaft to Pedestal.
Is there such a thing as a Pillow Block that is not self-aligning?
Yes, there are Rigid Blocks available.
Frankie, at times I hear the term “Felt Seal Series of Bearings”. What does that mean?
Years ago, before synthetics were so prevalent, they used actual felts for seals in bearings.
At times I will see a # like 16 or 24 or 26, etc. on the inner or outer race of a bearing in a mounted unit. What does that mean?
In may cases, that is the Ø of the shaft in 16ths of an inch.
Ex: 16/16 = 1”
24/16 = 1 ½”
26/16 = 1 ⅝”


Select a question from the list and I'll give you the answer!