Aug 14, 2026
A three-ton electric forklift that used to carry a full load up a ramp starts hesitating halfway. The battery is fully charged, the contactor clicks normally, and the motor spins when unloaded, but under load the truck jerks and the motor emits a faint shower of sparks. In many cases the real problem is not electronic at all: the motor's carbon brushes have worn below their useful limit. Once you know how forklift motor brushes behave, how to inspect them, and what to demand from a replacement part, you can diagnose this kind of failure in minutes instead of chasing phantom electrical faults.
This guide explains what forklift motor brushes do, where they are located, how to identify wear, how to replace them safely, and what to verify before ordering replacements.
Forklift motor brushes are replaceable carbon blocks that ride against the commutator of the forklift's DC motors. They are the sliding electrical contact that carries current from the stationary wiring harness into the rotating armature. Without a solid brush-to-commutator interface, the motor cannot develop full torque, and the contact point itself becomes a source of heat and arcing.
All industrial brushed motors work on the same principle, and carbon brushes also appear in AC and DC generator applications on other equipment. But forklift brushes deserve special attention because of their duty cycle: frequent starts, stops, direction changes, and high-current acceleration pulses. In a typical electric forklift, brushed motors perform three separate jobs at once — propelling the truck, raising the mast, and assisting steering. If any one of those motors loses brush contact, the whole machine behaves erratically.
Depending on the forklift design, you will find brushes in the traction motor, the hydraulic pump motor, and sometimes in a separate power-steering motor. The table below summarizes the role of each position and the symptoms that appear when brushes begin to fail.
| Motor position | Primary function | Typical symptom after brush wear |
|---|---|---|
| Traction motor | Drives forward and reverse travel | Jerky acceleration, loss of speed on ramps, sparking near the motor |
| Hydraulic pump motor | Powers the lift pump for raising and lowering loads | Slow or weak lifting, motor labors under rated load |
| Steering motor | Provides hydraulic or electric steering assist | Intermittent steering effort, unusual brush whine |
Because every one of these motors is frame-mounted and partially enclosed, brush wear is often invisible during a quick walk-around inspection. The motor keeps running, but long before the brushes stop working completely, they start to underperform in ways that are easy to mistake for battery or controller problems.
Carbon brushes are designed with a minimum usable length, and a set of brushes normally lasts between 1,500 and 2,500 operating hours in continuous logistics use, depending on load cycles, floor conditions, and motor ventilation. Rather than waiting for a breakdown, schedule inspections at planned service intervals and look for the following signs:
If the forklift is losing power but battery voltage, contactor operation, and the motor controller all check out, remove the brush caps and inspect the brushes before ordering any electrical replacement parts. A brush that looks usable from the outside can still be glazed or have a dislodged pigtail wire; verify both the visible length and the firmness of the connection between the brush and its flexible copper lead.
Replacing brushes is not a difficult job, but it is one where procedure matters more than tooling. The lower traction motor on many counterbalance forklifts is mounted beneath the truck body. Reaching the brush holders often requires either removing the motor or rolling it sideways, and a heavy motor that is not properly supported can drop, pivot, or crush whoever is underneath. Disconnect the battery, lower the forks completely, chock the wheels, and apply the parking brake before beginning. On models where the motor must be tilted, use a rated jack or a transmission jack to support the housing.
A worn brush leaves residues on the commutator surface. Before installing new brushes, clean the commutator carefully with a nylon or brass brush to loosen embedded carbon and copper dust. Avoid steel brushes, especially on soft copper or aluminum commutator segments, because they can score the surface and create higher wear for the new brushes. For stubborn deposits, use a mild solvent and wipe the commutator clean, then blow out the brush holder with dry compressed air so the new brushes slide freely.
Every new brush should move without sticking in its holder, and the pigtail should be oriented so it does not touch the commutator or adjacent metal parts. After fitting both brushes, rotate the motor by hand or run it unloaded for a short period to allow the brush faces to seat against the commutator. Then measure no-load current to confirm the motor is not drawing excessive amperage. Before returning the forklift to service, inspect the new brushes again after the first 8 to 10 hours of work, since this is the period in which most seating problems appear. You can find more detailed carbon brush replacement precautions in our separate maintenance guide.
Forklift motor brushes are not interchangeable standard parts. Even two motors of the same nominal power may use different brush geometries, spring systems, and material grades. A brush that is too soft wears out quickly; one that is too hard damages the commutator. Before ordering a replacement, record the following data from the old brush and from the motor nameplate:
Material selection has a direct impact on both brush life and commutator wear. Copper-graphite brushes carry higher current density with lower contact voltage drop, which makes them the standard choice for traction and hydraulic pump motors. Electrographite brushes run cooler in the absence of copper but generally require a drier, less contaminated environment. If your operation runs forklifts in an abrasive dust environment, such as a cement plant or a bulk fertilizer warehouse, compare the brush grade with the seasonal dust level before choosing a standard copper-graphite replacement. Our comparison of household motor carbon brushes vs industrial brushes explains the material trade-offs in more detail for engineers who need to document their selection.
The difference between a dependable replacement brush and a frustrating one is usually not visible in a product photo. It is in the consistency of the graphite compound, the crimp quality of the pigtail, the polishing of the contact radius, and the batch-to-batch traceability of the final product. A forklift with a long duty cycle will expose these differences faster than a workshop tool that runs for minutes at a time.
Jiangsu Hailing Carbon Products Co., Ltd. has focused on precision carbon brush manufacturing for more than 20 years, and reached a production capacity of 15 million brushes per month in 2019. The company holds IATF 16949, ISO 14001, and ISO 45001 management system certifications, and runs its own new manufacturing facility for Jiangsu Mincheng Carbon Technology, which adds roughly 16,000 square meters of production floor. For forklift owners who need a dependable replacement source, the dedicated forklift carbon brush product range covers the typical brushed motor positions used in electric forklifts, with the option of custom engineering when an existing brush does not match the holder geometry, spring position, or pigtail termination.
Ignoring worn forklift motor brushes is a costly way to save a few hours. The brush set is one of the lowest-priced components in the traction system, yet it protects one of the most expensive ones, the commutator and armature. Inspect at regular intervals, replace the worn sets before they reach the limit, and choose a supplier that can document its material grades and production controls. That combination will keep your forklift running predictably through the shifts that matter.
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