ASVAB Automotive Information Practice Test 790735

Questions 5
Topics Actuators, Brakes, Firing Order, Water Pump

Study Guide

Actuators

Actuators receive signals from the powertrain control module and carry out adjustments needed based on the data the PCM received from the sensors.

Brakes

Brakes utlize friction to slow vehicle tires. Drum brakes employ a cast iron drum that roates with the vehicle axle. When hydraulic pressure is applied to the brake assemblies at the wheels, internal pistons expand and push brake shoes outward into contact with the brake drum slowing the rotation of the axle. More powerful disc brakes operate by pinching a rotating disc betweeen two brake pads and allow for a larger surface area to contact the disc, provide more force, and are more easily cooled.

Firing Order

The stroke cycle of an engine is governed by the crankshaft which serves to regulate the firing order of the cylinders. All cylinders are not on the same stroke at the same time and correct firing order is important to balance engine operation and minimize vibrations. A common firing order for four-cylinder engines is 1-3-4-2 which indicates that cylinders 1 and 3 fire (power stroke)together and cylinders 4 and 2 fire together.

Water Pump

The water pump is driven by a belt connected to the crankshaft and ensures that coolant moves through the engine and radiator.