In a number 65 chain, what does the '5' denote?

In a number 65 chain, the '5' specifically indicates the pitch of the chain, which is the distance between the centers of two consecutive pins. In this case, the '5' denotes that it has a pitch of 5/8 inches. This type of designation is essential in understanding the dimensions and compatibility of the chain with sprockets and other components in a power transmission system.

The reference to roller-less chains is incorrect; a chain is typically categorized either as a roller chain or a roller-less chain based on its design. A roller chain would usually have rollers to facilitate smoother operation and less wear. However, in the case of a number 65 chain, it is a standard roller chain with a larger pitch, not a roller-less type.

The heavy-duty labeling is not accurate based solely on the '5' in the designation; heavy-duty characteristics involve additional specifications, such as material strength and design features beyond just the pitch. Similarly, while chains can be made from various materials, the '5' in the designation does not indicate material composition. The primary focus of the '5' is the pitch measurement relevant to the functioning of the chain in a system.