Wheel Loader Glossary

This Wheel Loader Glossary is designed to decode the technical language for everyone, from new operators to seasoned buyers. We’ve compiled and clearly defined the key terms you need to know, turning complex specs like “breakout force” and “articulation” into simple, understandable concepts.

Confused by wheel loader jargon? You’re not alone. Use this guide to operate more safely, choose the right machine, and speak the language like a pro.

A

• Articulation: The ability of the wheel loader to pivot at its center hinge, allowing the front and rear frames to turn independently. This provides a shorter turning radius for greater maneuverability in tight spaces.
• Articulation Angle: The maximum angle, measured in degrees, that the machine can articulate left or right from the center.
• Auxiliary Hydraulics: Additional hydraulic circuits beyond the main lift and tilt functions. They are used to power attachments like hydraulic hammers, brooms, or cold planers.

B

• Backhoe Attachment: A hydraulically powered excavating arm that can be attached to the rear of some larger wheel loaders, making them a combination machine (e.g., “loader-backhoe”).
• Breakout Force: The amount of force (measured in pounds or kilonewtons) the loader arms can generate to pry or “break out” material from a pile. It is a key indicator of digging power.
• Bucket Capacity: The volume of material a bucket can hold. It is typically measured in cubic yards (yd³) or cubic meters (m³).
  • Struck Capacity: The volume inside the bucket when the material is leveled flush with the top edge.
  • Heaped Capacity: The volume inside the bucket plus the material heaped on top at a specific angle of repose (e.g., 2:1).
• Bucket Cylinder: The hydraulic cylinder that controls the tilt (or dump) function of the bucket.
• Boom (or Lift Arms): The main structural arms that connect the bucket to the machine’s chassis and are raised and lowered by the lift cylinders.

C

• Center Pin / Hinge Pin: The large, central pin around which the machine articulates.
• Counterweight: A heavy weight, typically at the rear of the machine, used to balance the heavy load in the bucket and prevent tipping.
• Cylinder: A hydraulic component that converts fluid power into linear mechanical force. Wheel loaders have lift cylinders (for the boom) and tilt cylinders (for the bucket).

D

• Differential Lock: A feature that locks the left and right wheels on an axle together, forcing them to turn at the same speed. This provides maximum traction in slippery or muddy conditions.
• Dump Height: The maximum height (measured to the bottom of the bucket) the loader can reach when the arms are fully raised and the bucket is dumped forward. Critical for loading trucks.
• Dump Angle: The angle the bucket tilts forward when dumping, ensuring a complete and clean release of the material.
• Dump Reach: The horizontal distance from the front tires to the edge of the bucket at maximum dump height. Determines how far into a truck bed or hopper the loader can place material.

E

• Operating Load (EOL): A calculated value that ensures the machine remains stable during operation. It considers the machine’s tipping load and applies a safety factor.

F

• Four-Wheel Drive (4WD): A drivetrain system where power is delivered to all four wheels, providing superior traction and pushing power. Standard on virtually all wheel loaders.
• Frame: The main chassis of the machine. Wheel loaders have a two-piece Articulated Frame consisting of a front frame and a rear frame connected by the articulation joint.

G

• Gradeability: The maximum slope (expressed as a percentage) a wheel loader can climb while maintaining traction and power.
• Ground Pressure: The amount of force exerted on the ground by the tires. Lower ground pressure (often achieved with wider tires) is better for working on soft, unstable surfaces.

H

• Horsepower (HP): A unit of measurement for engine power.
• Hydraulic System: The network of components (pump, valves, cylinders, hoses) that use pressurized fluid to perform work, such as lifting the arms and tilting the bucket.

L

• Lift Cylinder: The hydraulic cylinder(s) that raise and lower the boom (lift arms).
• Linkage: The mechanical system that connects the bucket to the boom. Common types include:
  • Z-Bar Linkage (Volvo-type): Provides high breakout force and excellent load retention.
  • Parallel Linkage: Keeps the bucket in a more parallel position throughout the lift range, ideal for grading and finish work.
• Load Sensing Hydraulics: An intelligent hydraulic system that adjusts flow and pressure based on demand, improving fuel efficiency and reducing heat.

O

• Oscillation: The ability of the axle to pivot, allowing the wheels on one side to move up and down independently of the other. This helps keep all wheels in contact with uneven ground for better stability and traction.

P

• Payload: The actual weight of the material being carried in the bucket.
• Pin-on Attachment: An attachment that connects directly to the machine’s linkage using pins. Replacing it requires manually removing the pins.

Q

• Quick Coupler / Quick Attach: A hydraulic or mechanical system that allows the operator to switch between different attachments (forks, brooms, buckets) quickly and easily from the cab, without leaving the machine.

R

• Reach: The horizontal distance from the front axle to the center of the bucket. A longer reach is beneficial for loading high-sided trucks and precise placement.
• Rimpull: The tractive force available at the tire-to-ground interface to propel the machine. It is a key measure of pushing and loading capability.
• ROPS (Roll-Over Protective Structure): A certified cab or frame that protects the operator in the event of a machine rollover. Often integrated with the FOPS (Falling Object Protective Structure).

S

• Service Weight: The total weight of the machine including standard equipment, all fluids (fuel, coolant, oil), and a full-time operator.
• Static Tipping Load: The minimum load in the bucket that will cause the machine to tip forward when the lift arms are fully raised and the machine is on a firm, level surface. A key stability metric.
• Steering Axle: The front axle on a wheel loader, which is also the one that is steered.

T

• Tipping Load: See Static Tipping Load.
• Torque: A measure of rotational force produced by the engine, crucial for pushing into piles and climbing grades. Measured in lb-ft or Nm.
• Travel Speed: The maximum speed the machine can achieve, typically measured in miles per hour (mph) or kilometers per hour (km/h).
• Turn Circle / Turning Radius: The smallest circle the outside of the machine can turn within. Articulated steering gives wheel loaders a very small turning radius.

Z

• Z-Bar Linkage: See Linkage.