CAPTO™ EFFICIENCY TEST

TEST METHOD

CAPTO is designed with a 44.5 mm (1.75 in) diameter needle roller bearing pulley for efficient hauling and ascending. Both the 11 mm and 13 mm CAPTO models have the same pulley design and the same efficiency. To generate data on CAPTO’s pulley efficiency, a series of raises and lowers were performed using a 100 kg (220.46 lb) test mass and Teufelberger KM III in diameters 10.5 mm, 11 mm, and 13 mm.

Tests were performed using the methods outlined by Richard Delaney for standard testing of pulley efficiency, available via RopeLab. Tests were conducted in a controlled laboratory environment using a fresh rope sample from a single lot of new rope for each rope size. For each rope size, three intervals of raising and lowering were performed. The force required to raise the test mass at a constant speed was recorded by placing a load cell inline with the rope being run 180° over the pulley in a 1:1. The results from each interval were averaged and used to calculate raising, lowering, and combined efficiency data as shown below.*

*Note: Due to variables that are difficult to reproduce, this data is given for information only. Efficiency (EFF) is calculated by dividing the theoretical force required to raise the load by the measured force required.

CALCULATIONS

Raising efficiency is often the most practical measurement because it represents the force required to raise a load when hauling and ascending. Lowering Efficiency is not as useful in practice as Raising or Combined Efficiency, but it is easily calculated from the data gathered. Combined efficiency is a helpful data point for determining approximate efficiency using the CAPTO pulley for either raising or lowering. Below is a description of each calculation.

• Raising Efficiency = Test Mass Weight / Raising Average Force
• Lowering Efficiency = Lowering Average Force / Test Mass Weight
• Combined Efficiency = √ (Lowering Average Force / Raising Average Force)

KEY TAKEAWAYS

• Raising efficiency ranged from 87.9% to 91.4% depending on rope diameter.
• Lowering efficiency ranged from 84.1% to 85.5% depending on rope diameter.
• Combined efficiency ranged from 86% to 88.4% depending on rope diameter.
• Raising efficiency using 11 mm KM III in a 1:1 averaged 90.8%, placing CAPTO between the MPD and HD4 Pulley.
• Combined efficiency using 11 mm KM III averaged 87.4%, placing CAPTO between a 1.5″ and 2.0″ ProSwivel Pulley.
• The larger the rope diameter, the more energy is lost in bending the rope, causing a slight decrease in efficiency.
• Both the 11 mm and 13 mm CAPTO models have the same pulley design and the same efficiency.