From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Bulletin explaining the correct procedure for measuring fan belt sheave angles using 'Angle Cards'.
| Identifier | ExFiles\Box 135\1\ scan0097 | |
| Date | 9th December 1937 guessed | |
| FAN BELT BULLETIN #101 SUBJECT: MEASURING FAN BELTS CORRECTLY Gentlemen: It is not possible to secure in Denver the specifications of all makes and models of trucks, tractors and other equipment using V-belts. We attempt to keep our files up to date and we believe within a reasonable length of time a large part of the specifications on the current year's equipment may be available. Even when such a time does arrive, it will still be impossible to have 100 per cent replacement information, as many vehicles are built special and never appear elsewhere except in the territory for which they are ordered. Then, too, there is frequently the possibility of the fan assemblies having been changed, making our belt an improper fit. In view of these circumstances, we have designed a set of "Angle Cards" with which it is possible to accurately measure fan assemblies in the field. After this information has been secured, it can be sent to our Engineering Department for the determination of the correct replacement belt. These "Angle Cards" have been cut in increments of two degrees, 28 through 40, and are accurate enough for the best replacement measurements. MEASURING PROCEDURE Sheave Angle The sheave angle is the most important factor of a correctly fitting belt. To secure the correct sheave angle, select the "Angle Card" which most accurately fits the sheave groove. If necessary tear off a small quantity from the bottom of the card in order that the card will not ride on the bottom of the pulley groove. [Image 1: A V-belt pulley groove with an angle card labeled 40°. The card is too wide and sits high in the groove.] Angle Card too large- [Image 2: A V-belt pulley groove with an angle card labeled 32°. The card is too narrow and sits at the bottom of the groove.] Angle Card too small- [Image 3: A V-belt pulley groove with an angle card labeled 36°. The card fits correctly, touching the sides of the groove without bottoming out.] Angle Card Correct | ||