Question 445Electricity & Electronics - Assistant Engineer

The correct answer is B) spring scale. The proper brush pressure in a DC propulsion motor is established using a spring scale. This allows the technician to measure the exact pressure being applied by the brushes against the commutator, which is crucial for ensuring proper contact and electrical performance. The spring scale provides a direct reading of the force being applied, which can then be adjusted as needed to meet the manufacturer's specifications. The other options are incorrect because they are not the proper tool for measuring brush pressure. A manometer measures fluid pressure, a compound gauge measures both pressure and vacuum, and a multimeter measures electrical parameters but not physical force.