What are the types of motor belts?
3 Answers
Motor belts are divided into seven types: O-type, A-type, B-type, C-type, D-type, E-type, and F-type. The cross-sectional area of the belt gradually increases from O-type to F-type. Below are the precautions for motor belts: 1. When purchasing belts: The selected type should be compatible with the chosen V-belt. Otherwise, the V-belt may exhibit abnormal conditions in the pulley groove. When replacing V-belts, it is best to bring the old belt to ensure the correct type is purchased. 2. When replacing belts: If two or more V-belts need to be replaced, use the specified type of V-belt and ensure that the tension of each group of V-belts is consistent. Mixing old and new belts or reducing the number of belts is not allowed. Otherwise, the old and new V-belts will bear uneven force, and the old V-belts may even become ineffective, affecting power transmission and shortening the lifespan of the V-belts.
The motor belt is actually quite particular, with the model mainly depending on the vehicle's alternator structure. There are two common materials: raw-edge belts and wrapped belts. Raw-edge belts dissipate heat quickly and are suitable for high-revving models. Japanese cars often use the 6PK series, for example, 6PK2245 means 6 ribs and a total length of 2245mm. German cars prefer multi-rib belts, with specifications like 7×16×1325 representing 7mm width, 16mm thickness, and 1325mm circumference. The AX models used in older cars are basically obsolete, replaced by low-noise designs like PK and PJ. Before buying a belt, it's advisable to measure the circumference of the old part and check the tensioner pulley condition, as worn pulley grooves can accelerate belt cracking. Major brands like Gates and Bando offer a full range of models, but don't cheap out on no-name brands—snapping one mid-drive might leave you calling for a tow truck.
Last time I repaired my car, I found that belt models mainly depend on three numbers: width, angle, and circumference. For example, 5PK1340 means a 5-rib V-ribbed belt with a 1340mm circumference. There are significant differences between car models—Honda tends to use 6PK2135, while Toyota commonly uses 4PK870. The new trend is double-sided toothed belts, which can transmit force on both sides, with model numbers ending in XS. When selecting a belt model, pay attention to two things: first, check the original specifications in the manual, and second, measure the circumference on-site by wrapping a string around the pulley. Belt lifespan is actually related to the condition of the pulley system—a stuck idler pulley can cause new belts to squeal. I usually recommend BANDO or Michelin belts, as their durability is three times higher than no-name brands. When replacing a belt, always check the water pump pulley—if it’s misaligned, replace the entire pulley system to avoid rework.
