running gear
The wheels, suspension, steering, powertrain and usually the chassis of a motor vehicle.
running gear: the moving parts that make a vehicle go
Running gear refers to every component on a motor vehicle that enables it to move, steer, and stop: the wheels, axles, suspension, steering linkage, transmission, driveshaft, and the frame or chassis that holds everything together. On a truck or industrial vehicle, these parts are what engineers inspect and suppliers stock as separate line items. The term distinguishes the mechanical and structural essentials from the body, cab, and auxiliary systems.
The composition of running gear depends on the vehicle class and duty. A heavy-duty truck running gear includes rigid axles with multiple wheels per side, leaf spring or air suspension, a robust frame rated for payload, and a transmission matched to engine torque. A light commercial vehicle might use independent front suspension with coil springs, simpler steering geometry, and a lighter chassis. Agricultural or construction machines modify the basic running gear with reinforced axles, all-terrain tires, and sometimes tracks instead of wheels.
Why suppliers and mechanics think in running gear terms
Fleet managers and maintenance crews buy and replace running gear components as assemblies or systems. A wheel bearing, brake hub assembly, suspension arm, and driveshaft all fall under running gear procurement. When a vehicle has "worn running gear," it means frame flex, play in steering, wheel wobble, or transmission slip: the signs that the foundational systems are losing precision and safety. Conversely, a vehicle with "tight running gear" handles predictably and wears tires evenly.
The term becomes practical when specifying parts across a fleet. A supplier might advertise "OEM running gear kits" for a specific truck model, bundling wheels, bearings, seals, and fasteners to simplify ordering and reduce assembly time in the workshop. This is cheaper than sourcing each item separately and ensures compatibility.
Running gear is distinct from the powertrain in some usage: the engine, fuel system, and cooling system are separate concerns. However, older texts sometimes include the engine itself within running gear, so context matters. In modern supply chains, running gear usually stops at the transmission output; what happens beyond that shaft belongs to the chassis, suspension, or drivetrain specialists.