Question 1

Hydrostatic Drive System

Accepted Answer

A closed-loop hydraulic system utilizing a pump and motor to transmit power to the equipment's wheels or tracks.

Question 2

Oscillating Axle

Accepted Answer

A pivoting axle that allows the machine to maintain contact with uneven terrain, improving traction and stability.

Question 3

Torsional Damper

Accepted Answer

A device used to absorb and dissipate torsional vibrations in the drivetrain, reducing stress on components.

Question 4

Differential Lock

Accepted Answer

A mechanism that locks the differential, forcing both drive wheels or tracks to rotate at the same speed, improving traction.

Question 5

Wet Multi-plate Clutch

Accepted Answer

A type of clutch utilizing multiple friction plates immersed in oil to engage and disengage power transmission.

Question 6

Load Sensing Hydraulic System

Accepted Answer

A hydraulic system that adjusts flow and pressure based on the load requirements of the working attachment.

Question 7

Hydraulic Flow Divider

Accepted Answer

A device that splits the flow of hydraulic fluid between multiple circuits, ensuring equal flow rates.

Question 8

Swing Drive

Accepted Answer

A hydraulic motor and gearbox assembly responsible for rotating the upper structure of excavators and cranes.

Question 9

Planetary Gear Set

Accepted Answer

A compact, highly efficient gear set used in transmissions, final drives, and other heavy equipment applications.

Question 10

Counterbalance Valve

Accepted Answer

A hydraulic valve used to prevent hydraulic cylinders from dropping or drifting when pressure is removed.

Question 11

Pump Cavitation

Accepted Answer

The formation of vapor bubbles in the hydraulic pump due to low inlet pressure, leading to reduced performance and possible damage.

Question 12

Accumulator

Accepted Answer

A hydraulic component that stores energy in the form of pressurized fluid, providing a reserve for sudden demands.

Question 13

Hydraulic Schematic

Accepted Answer

A visual representation of a hydraulic system, displaying components, connections, and flow paths.

Question 14

Valve Spool

Accepted Answer

The movable part of a hydraulic valve that directs fluid flow when shifted.

Question 15

Hydraulic Pilot Control

Accepted Answer

A system that uses low-pressure, low-flow hydraulic signals to control the operation of higher-pressure, high-flow circuits.

Question 16

Variable Displacement Pump

Accepted Answer

A hydraulic pump that can adjust its output flow based on system demand, improving efficiency.

Question 17

SAE J1939

Accepted Answer

A standardized communication protocol for electronic control units (ECUs) in heavy-duty vehicles and equipment.

Question 18

Injector Sleeve

Accepted Answer

A replaceable metal insert in the cylinder head that seals the injector and protects the head from combustion heat and pressure.

Question 19

Diesel Particulate Filter (DPF)

Accepted Answer

An exhaust aftertreatment device that captures and stores particulate matter, reducing emissions.

Question 20

Selective Catalytic Reduction (SCR)

Accepted Answer

An exhaust aftertreatment system that injects urea solution to convert NOx emissions into nitrogen and water.

Question 21

EGR Cooler

Accepted Answer

A heat exchanger that cools exhaust gases before they are recirculated back into the engine's intake, reducing NOx emissions.

Question 22

Viscous Fan Drive

Accepted Answer

A temperature-sensitive clutch that engages the engine cooling fan when needed, conserving power and improving efficiency.

Question 23

Precombustion Chamber

Accepted Answer

A separate combustion chamber in some diesel engines that promotes more complete combustion and reduces emissions.

Question 24

Injector Stiction

Accepted Answer

A condition where injector spool valves stick, causing poor performance or injector failure in diesel engines.

Question 25

Turbocharger Wastegate

Accepted Answer

A valve that bypasses exhaust gases around the turbocharger when boost pressure reaches a predetermined level, preventing overboost.

Question 26

Constant Mesh Gearbox

Accepted Answer

A transmission design where all gears remain in mesh at all times, reducing the potential for gear damage during shifting.

Question 27

Synchromesh Transmission

Accepted Answer

A manual transmission utilizing synchronizers to match gear speeds before engagement, allowing for smoother shifting.

Question 28

Powershift Transmission

Accepted Answer

A type of automatic transmission that allows for seamless gear changes without the need for a torque converter.

Question 29

Wet Disc Brake

Accepted Answer

A hydraulic brake system that uses oil-cooled multi-disc brakes to provide improved heat dissipation and reduced brake fade in heavy-duty applications.

Question 30

Air-over-hydraulic Brake System

Accepted Answer

A braking system that combines the benefits of compressed air and hydraulic fluid to provide powerful and precise braking control.

Question 31

S-cam Brake

Accepted Answer

A type of drum brake commonly used in heavy-duty vehicles, where an S-shaped camshaft rotates to expand the brake shoes against the drum.

Question 32

Automatic Slack Adjuster

Accepted Answer

A self-adjusting mechanism that maintains proper clearance between the brake shoes and drum in air brake systems.

Question 33

Air Dryer

Accepted Answer

A component in the air brake system that removes moisture and contaminants from compressed air before it reaches the air reservoirs.

Question 34

Air Governor

Accepted Answer

A device that controls the air compressor's cut-in and cut-out pressures, maintaining the air brake system's required pressure levels.

Question 35

Jake Brake

Accepted Answer

An engine brake that uses the engine's compression and exhaust valves to create a braking force, helping to slow the vehicle down.

Question 36

Retarder

Accepted Answer

A device used to supplement the vehicle's service brakes, providing additional braking force through the driveline or transmission.

Question 37

Wheel-end Assembly

Accepted Answer

The combination of components at the end of the axle, including the hub, bearings, brake assembly, and wheel fasteners.

Question 38

Kingpin

Accepted Answer

The main pivot point in the steering system of a heavy-duty vehicle, allowing the front wheels to steer while supporting the weight of the vehicle.

Question 39

Tie Rod End

Accepted Answer

A ball-and-socket joint that connects the steering linkage to the steering knuckle, allowing for the transfer of steering force.

Question 40

Center Bearing

Accepted Answer

A support bearing located between the two halves of a two-piece driveshaft, reducing vibration and maintaining proper alignment.

Question 41

Universal Joint

Accepted Answer

A flexible coupling used in driveshafts to transmit torque between misaligned shafts while allowing for angular movement.

Question 42

Final Drive

Accepted Answer

The last set of gears in the drivetrain that transfers power from the transmission or differential to the drive wheels or tracks.

Question 43

Track Tensioner

Accepted Answer

A device that maintains proper tension on the tracks of tracked equipment, preventing track derailment and reducing wear.

Question 44

Track Adjuster

Accepted Answer

A mechanism used to adjust the position of the front idler wheel, allowing for changes in track tension.

Question 45

Track Grouser

Accepted Answer

A raised bar or cleat on a track shoe that improves traction and prevents the track from slipping on the ground surface.

Question 46

Track Shoe

Accepted Answer

The individual metal plates that make up the tracks on tracked equipment, providing a large contact surface for improved traction and reduced ground pressure.

Question 47

Swing Bearing

Accepted Answer

A large, circular bearing that supports the upper structure of excavators and cranes, allowing for 360-degree rotation.

Question 48

Boom Float

Accepted Answer

A hydraulic function that allows the boom of an excavator to follow the ground contour without operator input, reducing the risk of damage and improving efficiency.

Question 49

Lift Capacity Chart

Accepted Answer

A visual representation of the maximum load an equipment can safely lift at various distances and boom angles.

Question 50

Stability Triangle

Accepted Answer

The area between the three points of contact (tires or tracks) of a piece of equipment, within which the center of gravity must remain to prevent tipping.

Heavy Duty Equipment Technician - Red Seal Exam Flashcards