Rotary Joint (31577)

Reference Folder: 31577_RotaryJoint

The Rotary Joint 903-140-188-IC (TRAK P/N: 31577), also referenced as Kit 34204, requires tight tolerances to operate safely at high spindle speeds. The critical region is the "Customer Interface" section of the drawing 903-140-188-IC, which defines acceptable concentricity and perpendicularity for the rotary joint mounting surface.

Before installing or replacing the rotary joint, inspect the rear spindle interface for any wear or distortion. Damage from a failed union may push it out of spec.

If any rework is required to the spindle shaft or its rear interface, please provide the spindle serial number to TRAK Technical Support. We will coordinate with Royal Products (spindle OEM) for model-specific repair procedures.

Tighten the rotary joint bolt (24 mm hex) to 35 Nm, equivalent to 25.8 ft-lbs.

18 mm Pin Gauge Fit Check

• Insert an 18mm pin gauge into the spindle’s rear locating bore.
• Diameter Spec: Ø17.995 mm +0.005 mm
• It should seat snugly to confirm the bore diameter is correct and undamaged.

Perpendicularity – Spindle Mounting Face

• Mount a dial indicator to the machine frame.
• Sweep the rear spindle face where the rotary joint will bolt on.
• Max Perpendicularity TIR: 0.005 mm (0.0002")
• This ensures the face is square to the spindle axis.

Concentricity of Locating Bore

• With the pin removed, sweep the inner wall of bore.
• Max Concentricity TIR: 0.007 mm (0.00028")
• This confirms the bore is concentric to the spindle’s rotational axis.