Genuine Makita part 516311-8 — Armature (rotor) assembly, 115 V — direct-fit for the Makita HR4000C SDS‑max rotary hammer.
What it is and why it matters: this is the complete rotor/armature subassembly (commutator, laminated core with windings, cooling fan and drive shaft) that replaces a worn or shorted rotor and restores the motor’s rotating magnetic field and commutation. The HR4000C service/parts breakdown and technical notes list the armature as the item to replace when the motor shows burnt windings, heavy sparking at the brushes, or no rotation.
Fitment and notes: listed specifically for the HR4000C rotary hammer (115 V / T1 configuration).
Installation tip (brief): the armature installs into the motor housing and into the field assembly; when replacing it you’ll commonly fit new bearings, check brush condition, and reinstall the commutator end components to factory torque — the HR4000C parts diagram shows the related components and order of reassembly.
If you need this specific item to return an HR4000C to service, the 516311-8 armature is the exact Makita numbered replacement called out for that model and voltage configuration.
(Part numbers and fitment above are taken from Makita parts listings and HR4000C technical/parts breakdowns.)
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