NACHI40TAB09DTBall Screw Support Bearing 40x90x20mm 60 Degree Thrust Angular Contact ABEC 5 P5 One Bearing (Half of Tandem Pair)

Product Description

What this part is

A Nachi 40TAB09 ball screw support bearing: a 60° thrust angular contact ball bearing, 40 mm bore x 90 mm OD x 20 mm wide, in ABEC 5 (P5) precision class. These live at the fixed end of a machine tool ball screw, where the entire feed force of the axis arrives at the bearing as pure thrust.

Decoding the designation

40 — 40 mm boreTAB — Nachi thrust angular contact ball screw support series, 60° contact angle09 — series size code; 90 mm outside diameterDT — duplex tandem, the arrangement the full set is built forP5 — ABEC 5 precision class-1/2PR — half of a pair

Quantity and configuration

This listing is ONE bearing. The -1/2PR suffix means half of a pair, so although the base designation is a DT (tandem) set, what is supplied here is a single bearing out of that set. A single 60° bearing takes thrust in one direction only. If the screw end needs the full tandem pair, order two; if it needs a DB arrangement to locate the screw both ways, that is a different stack again.

Why this is not an ordinary angular contact bearing:
Ball screw support bearings are their own family and get mis-specified constantly. A 60° contact angle gives up radial capacity and speed to gain very high axial capacity and, more to the point, very high axial stiffness — and axial stiffness is what keeps a CNC axis positioning accurately under cutting load. A 15° or 25° angular contact bearing of the same 40 x 90 x 20 envelope will drop straight into the housing and quietly ruin the axis. Genuine members of this family across brands are NSK TAC, FAG 7602 series, NTN BST, Timken MM…BS and RHP BSB.

Published specifications

Bore: 40 mmOutside diameter: 90 mmWidth: 20 mmContact angle: 60°Bearing type: thrust angular contact ball, ball screw supportPrecision class: P5 / ABEC 5Base arrangement: duplex tandem (DT)Rows: 1Closure: open

Fitting notes

Identify the thrust face before assembly — these bearings are strongly direction-sensitive and a reversed bearing carries no load at all in the direction that matters. Clamp the stack as a unit and tighten the screw-end lock nut to the machine builder’s figure; a loose lock nut is the usual cause of lost axis stiffness that gets blamed on the ball screw itself. Where this bearing is combined with others, match the full designation and precision class across the stack. Mount clean, press only on the ring being fitted, and keep the grease charge modest.

Interchange guidance

Search terms include 40TAB09DT, 40TAB09-DT-P5, 40TAB09DTP5 and the base 40TAB09. Genuine cross-brand equivalents in the same 60° family and envelope are NSK 40TAC90B, NTN BST40X90 and FAG 7602040-TVP. Related but NOT interchangeable: any 15°, 25° or 40° angular contact bearing on the 7208-type envelope, and a higher or lower precision class than P5. Contact angle and arrangement both have to match.