🔍 Key Concepts

• Single vs double reduction – count how many distinct gear stages the power passes through from input shaft(s) to output shaft • Single vs double input – look at how many separate pinion shafts are bringing power into the main (bull) gear • In a combining gear for dredges/tugs, two engines often drive one propeller shaft through one large bull gear

💭 Think About

• From each engine input shaft, trace the path of power to the output shaft: how many gear meshes are there in series? • Look at the number of pinions that mesh with the large bull gear – does the drawing show one driving pinion or two? • Ask yourself: does this gear set change speed in one step or in two separate steps before reaching the output? That determines single vs double reduction.

✅ Before You Answer

• Carefully count the number of input shafts/pinions that engage the main bull gear • Verify whether there is only one large bull gear on the output shaft, or if there is a second, smaller intermediate shaft with its own gear pair (which would indicate double reduction) • Confirm that the output shaft is directly driven by the large bull gear rather than through an additional reduction stage