Technical

Due to the diverse ranges of chains now available, this article will look at chains which are fabricated from steel, have link plates, bushes and pins and are assembled with an interference fit complete with pin ends that are spun or riveted. This type of chain includes standard roller transmission chains and engineered steel or conveyor chains. Examples of chains that are not covered include cast link, silent running, leaf chain and those that are molded from plastic such as integral slat chains/flat top chains.

British Standard Chain Numbering

BS chains are measured in 16ths of an inch.  For chains 06B and larger, the pitch can be found from dividing the chain number by 16 i.e.

06B Chain Pitch (mm) = 06/16 × 25.4 = 9.525mm

A hyphenated number after the initial chain number indicates the number of chain strands. For example, 24B-1 is a single strand, 24B-2 is two strands and 24B-3 is three strands.

ANSI Chain Numbering

ANSI chains are measured in 8ths of an inch, but the right-hand digit of the chain code also designates if the chain is standard (0), lightweight (1) or rollerless (5).

For example, a 41 chain would be a lightweight chain with a 4/8” pitch while 100 chain would be standard, having a pitch of 10/8”.

‘H’ after the chain number designates the chain as ‘Heavy’, adding an extra 1/32” to the thickness of the standard link plate. For example, a 100H chain would have a 4.8mm thick link plate instead of the standard 4mm thick plate.

A hyphenated number after the initial chain number indicates the number of chain strands. For example, 100-1 is a single strand, 100-2 is two strands, 100-3 is three strands and 100H-2 is heavy duty 100 series chain with 2 strands.

ANSI Roller Chain Proportions

ANSI roller chains have major dimensions that are roughly proportional to the chain pitch. These proportions were obtained through research and experimentation and are used for chains that conform to ASME B29.1;

Roller width ≈ 5/8 of the pitch.
Chain (roller) width ≈ 5/8 of the pitch.
Pin diameter ≈ 5/16 of the pitch.
Link plate thickness ≈ 1/8 of the pitch.
Maximum roller link plate height ≈ 0.95 × pitch.
Maximum pin link plate height ≈ 0.82 × pitch.

Anti-friction, rolling contact or rolling element are terms used to describe bearings that support axial and/or radial forces, while allowing rotation, using rolling contact elements rather than sliding contact elements. Numerous basic designs of bearings are available and bearing selection generally depends upon the type of supported forces/loads, speed, lubricant, size, life requirements and cost.  It should also be noted that at lower speeds, the frictional forces within a bearing are twice that of the same bearing running at high speed, which can directly affect the life of a bearing.  Bearing failure should generally occur due to fatigue of the races or rolling elements, with other failure methods being investigated and remedial action to the system being implemented.

V-Belt pulleys are generally manufactured from steel, or a fine grain cast iron. Steel pulleys are generally used for smaller V-belt sizes, while cast iron is used for larger diameters or multiple V-belt drives and offers a small flywheel effect on larger sizes. It should also be mentioned that the same pulleys can be used for both Wedge and Classical V belts.

Belts are the cheapest utility for power transmission between shafts that may not be axially aligned. Mechanical power transmission is achieved by specially designed belts and pulleys.

The demands on a belt-drive transmission system are large, and this has led to many variations of belts. They run smoothly, with little noise and cushion the motor and bearings against load changes, albeit with less strength than gears or chains.

However, improvements in belt engineering allow the use of belts in systems that only formerly allowed chains or gears.

There is an extensive array of shaft couplings available on the market today.  Each coupling type has its own benefits and drawbacks, but how does one go about deciding which coupling is suitable for a given system?

Keys are a common way of fastening items such as sprockets, pulleys and gearboxes on to cylindrical shafts. A key is defined by being a removable element that is capable of transferring torque between a shaft and a hub. In general, keys are either square or rectangular and are usually parallel/flat, although gib head keys for example utilise a taper.

Material mechanical properties form the basis of any component design, ensuring that the component can operate under the required working loads without changing its configuration or microscopic structure.  These properties are often found experimentally by using material test samples.  It is often the case when performing these experiments that two samples from the same material, tested on the same machine, give different values.  To ensure the safety of any component manufactured from a material, the property data is often given as the minimum range or value in their corresponding data table.