APM
All alarm codes
ALARM 261

Head lubrication alarm

Pressure switch (SP25, SP26 or SP27) in the spindle cooling unit has activated

Controls
T-Plus, T-32, Mazatrol 640T
Machine series
Quick Turn, SQT, Nexus, Mazak lathes on M640T (test rig: trochoid lube pump)

Causes

  1. Pressure switch (SP25, SP26 or SP27) in the spindle cooling unit has activated

    • HelmanCNCindustry_blog
      Mazak Alarm 261 is a HEAD LUBRICATION ALARM triggered when the pressure switch (SP25, SP26, SP27) in the spindle cooling unit has activated.

  2. Low headstock coolant level; faulty hose clamp on supply line causing slow leak; worn brass keys in the pump coupling so the motor no longer turns the pump; pump sucking air

    • HelmanCNCindustry_blog
      low coolant level in the headstock cooling system ... the supply line from the tank to the pump may have a faulty hose clamp that results in a slow leak ... Brass keys in the pump coupling can wear over time until the mo…

  3. Pressure switch SP4 (input X1F) on the trochoid pump outlet has failed open or is not seeing lube pressure — control thinks head lube isn't flowing.

    • Fabian Achavalyoutube
      Steps to perform are: 1) Dismount SP4 (X1F input) pressure switch and set a plug instead on the trochoid pump outlet install also a ball valve to close and t[est the alarm].

How to clear it

  1. 1

    Verify headstock coolant level; top up if low

  2. 2

    Inspect supply hose and clamp between tank and pump for slow leaks

    • HelmanCNCindustry_blog
      the supply line from the tank to the pump may have a faulty hose clamp that results in a slow leak
  3. 3

    For Mazak SQT headstock cooling units, refill with 50% distilled water + 50% Mobil long-life coolant

    • HelmanCNCindustry_blog
      the manufacturer recommends using distilled water 50% plus long life coolant (Mobil) 50%
  4. 4

    Dismount the SP4 pressure switch (input X1F) and replace with a flow meter on the trochoid pump outlet; install a ball valve so you can simulate flow loss and verify alarm clears when flow is present.

    • Fabian Achavalyoutube
      Dismount SP4 (X1F input) pressure switch and set a plug instead on the trochoid pump outlet install also a ball valve to close and test the alarm '261 Head Lubrication Alar[m]'

Additional notes

The 50/50 distilled water + Mobil long-life coolant recipe is attributed to Mazak guidance for SQT; verify against spec sheet before publishing.

Confidence: high · Auto-promoted to HIGH — cross-verified across 2 independent research runs (research_alarms_2026-05-21_partners, research_alarms_2026-05-21_social).

First sourced: 5/21/2026