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Gear & Pulley Manufacturing Glossary of Terms


Aluminum is the most common metal found on the Earth’s crust. It is notably light and thin, having about ⅓ the density of its metal counterpart, steel. Aluminum is used frequently in manufacturing settings.

Angular Misalignment

When two shafts in a piece of machinery become skewed, this is known as angular misalignment. This specific misalignment can result in unwanted torsion in machinery, causing unusual vibrations during utilization.

Bolt-On Flanges

Bolt-on flanges are known as the strongest and most durable flanges available for purchase. Flat head screws hold these flanges to the side of the pulley mechanisms. These flanges are removable if pulley maintenance is required at any given time.

Bore Size

Bore size is the diameter of the center hole in each pulley or gear. This center hole is used to mount the pulley or gear to a shaft often used with a keyway to assure no slippage between the shaft and pulley occurs.  


The circumference of a circle is, basically, the distance around the border of the circle. In the power transmission industry, the circle is a pretty common shape. To find the circumference of a given circle, simply multiply the diameter (distance across the circle) by pi (3.1415…). When it comes to pulley machinery, understanding the basics of the circle comes in handy, especially when looking at something such as gear ratios.

Drive Ratio

The ratio calculated between increased torque and decreased speed of machinery, or vice versa.

English-Metric Conversion

The two primary systems of measurement, English and Metric, are used all around the world. However, only a handful of countries — the United States and a few others — use the English system: the rest of the world functions on metric.

The English system uses inches, feet, miles, and pounds to measure quantities, while the metric system uses meters, liters, and grams to quantify these same measurements. In terms of weight, 1 kilogram is the equivalent of 2.2 pounds; likewise, 1 meter equals 3.28 feet. 


Located on the sides of the teeth, flanges could be described as the small “rings” found on the pulley. The pulley belt is held in place by these flanges, which sit on the outside of the belt path.

The importance of flanges is seen in the mitigation of angular misalignment — or the tendency of belts to relocate too far to one side or another.

Gear Ratios

Gear ratios have to do with gears working together in a system. A gear ratio of 2:1 communicates to the individual that one gear is twice as large as the other. And yes, the size of the gear does matter. It actually translates to the efficiency of the gear pair directly. Going back to circumference, a gear that has twice the circumference of another gear will only move half as fast as its half-sized counterpart.

Put simply, if the first gear has a circumference of 1 inch, and the next gear has a circumference of 2 inches, in order for the 1-inch gear to cover as much distance as the 2-inch gear, it has to move twice as fast.

The circumference of a gear also dictates the number of teeth on said gear. The bigger the gear, the more teeth on the gear. Counting the teeth on a gear is what dictates its gear ratio when compared to another gear.

Heat Shrinking

Large flanges, measured in diameter, are often attached to timing pulleys via heat shrinking. The process is simple: heat the flanges up to a specific temperature (450 degrees Fahrenheit), and set the hot flanges onto the pulleys’ flange step. When the flanges cool, they shrink into the perfect position upon the step.


Horsepower (HP), also referred to as “mechanical horsepower,” is found by calculating the work required in order to raise a weight of 33,000 pounds (lb) by 1 foot over the course of 1 minute. This term was created in the 1800s to equate the work of horses to the work of steam engines. 


A pulley is designed to aid the redirection of a rope or cable, often found in many different types of machinery.

Roll Staking

Roll staking serves as another way in which to attach flanges to timing pulleys of smaller proportions. Within this method, a crimp is formed around the edge of the flanges on 100% of the diameter, not just in a few key points. This yields a much better staking method for attaching flanges to a given pulley.

Set Screw

Also known as a “grub screw or blind screw,” a set screw is a piece of equipment used to secure two other pieces of machinery together, often without the use of a nut. It is often used to secure a pulley to a shaft.

Stainless Steel

Similar to steel in composition, stainless steel is commonly used in manufacturing and machinery. However, unlike steel, the composition of stainless steel prevents the metal from developing rust over time.


Steel is a metal composite made up of iron and carbon, as well as small amounts of silicon, phosphorus and other elements. This unique composition makes steel the most efficient and highly-used metal in engineering and construction.

Timing Belt

Also known as a “cambelt,” a timing belt operates in line with an engine’s intake and exhaust strokes. It ensures that each specific valve, whether for intake or exhaust, opens at the right time. This type of belt often works in tandem with the crankshaft and camshaft.

IPG offers an abundant variety of timing belt pulleys, with variations based on pitch, teeth count, bore size, keyways, setscrews, and more.


In the pulley industry, torque is the rotational equivalent of force. The more torque per rotation, the less speed necessary to produce the same amount of efficient work. The basic relationship is that an increase in torque yields a decrease in speed. This is known as the drive ratio.