SKF PHP 40-AT10-38 RSB metric synchronous timing belt pulley (also called timing sprocket or toothed pulley). 40 teeth, AT10 profile (10 mm pitch, trapezoidal metric AT-family tooth), 38 mm face width. Pitch diameter (PD) = teeth x pitch / pi = 40 x 10 / 3.14159 = 127.32 mm; outside diameter approximately 123.6 mm. The 38 mm FACE WIDTH accepts the matching SKF PHG AT10 timing belt in 25 mm or 32 mm belt width per SKF convention (belt narrower than face by 3-6 mm each side for tracking margin). IMPORTANT — 'RSB' in SKF PHP nomenclature = 'Rough Stock Bore' (also called pilot bore). The pulley ships with an undersized central bore that the customer machines or hones to the target shaft size, or bores to accept a Taper Lock bush separately purchased. RSB is NOT a taper-bush pulley. Taper-bush variants carry the TB suffix (e.g. PHP 28-8M-30TB) and are a different SKF part configuration. QD (Quick-Detach) bushed variants are the equivalent North American range. SKF prefix map for power transmission: PHP = pulleys / sprockets; PHG = timing belts; PHF = bushings and hubs (PHF TB Taper Lock series). Naming pattern for metric PHP: PHP<teeth>-<profile>-<face-width-mm><bore-suffix>. For imperial-pitch pulleys the pattern is PHP<teeth><profile><belt-width-in-hundredths-of-an-inch><bore-suffix> (e.g. PHP 18XL037RSB = 18-tooth XL 3/8 inch belt pilot bore). AT10 profile decoder: metric AT-family, 10 mm pitch, deep trapezoidal tooth with steel-cord tension member for zero-backlash bidirectional positioning. Sister profiles SKF stocks: AT5 (5 mm pitch), AT20 (20 mm pitch), T2.5 / T5 / T10 / T20 (older T-family trapezoidal), HTD 3M / 5M / 8M / 14M / 20M (curvilinear round-tooth, higher power density), imperial MXL / XL / L / H / XH (older imperial trapezoidal). AT10 is the workhorse for medium-power high-stiffness servo positioning. PHP AT10 typical tooth-count range from stock listings: 18, 20, 22, 24, 27, 30, 32, 36, 40, 44, 48, 60, 66, 72, 90 (not every combination stocked). PHP AT10 face-width options: 18, 30, 38, 55/56, 66 mm (matching 16, 25, 32, 50 mm belt widths with tracking margin). material: SKF PHP default is cast iron with phosphate corrosion coating (verified on XL and 8M range). AT10-38 material NOT independently verified against SKF's specific datasheet; expected to match the PHP family default unless customer specifies aluminium (some low-inertia servo-axis variants). Taper Lock bush fitment (for buyers boring the RSB to accept a bush): common Taper Lock bush series and typical shaft-range guide — 1108 (9-28 mm), 1210 (11-32 mm), 1215 (14-32 mm), 1610 (14-42 mm), 1615 (14-42 mm), 2012 (14-50 mm), 2517 (16-60 mm), 3020 (25-75 mm), 3030 (25-75 mm), plus larger 3535 and 4040. For a 40-tooth AT10 pulley (~127 mm PD boss) the typical fitted Taper Lock bush is a 2012 or 2517 — but final selection depends on the specific boss diameter published on the SKF technical drawing for this exact PHP 40-AT10-38 RSB SKU. Confirm from SKF datasheet before ordering the bush. Companion belt: SKF PHG AT10 open-length or endless synchronous belt (polyurethane body with high-tensile steel cord), naming PHG AT10-<length-mm>-<width-mm> (e.g. PHG AT10-1800-25 for a 1,800 mm-long 25 mm-wide belt). Available belt widths 16 / 25 / 32 / 50 mm. Direct cross-references (dimensional / profile equivalents, not SKF-approved crosses): Continental Synchroflex 40 AT10/32 (Continental ContiTech), Optibelt OMEGA and Optibelt ALPHA TORQUE AT10 40-tooth pulleys, Mulco Zahnriemenscheibe 40-AT10-32, Fenner (Megadyne) MEGAPOWER AT10 range. Note: Gates PowerGrip GT range does NOT offer AT10 — Gates uses 8M-GT and 14M-GT curvilinear profiles instead, which are a DIFFERENT profile and NOT a direct swap for AT10. Applications: servo positioning axes on CNC machine tools, servo-driven linear feed on gantry systems, robotic pick-and-place indexing, packaging line registration, printing-press line-of-action drive, semiconductor wafer-handling, general power transmission where zero-backlash bidirectional positioning with steel-cord dimensional stability is required. Sizing tool: SKF Belt Drive Design Calculations Tool (skf.com digital-tools) computes required tooth count, belt length and drive tensioner arrangement from application load, speed and geometry. Alternative sizing tools: Continental Belt Cross Reference tool (beltcrossreference.continental.com), Optibelt CAP, Gates DesignFlex. Datasheet reference: SKF Power Transmission Products Catalogue publication 11015 EN. cBallast supplies the full PHP synchronous pulley range plus matching PHG AT10 belts, Taper Lock bushes (PHF TB series) and installation tooling ex-EU stock. Request a quote by pulley SKU (e.g. PHP 40-AT10-38 RSB), matched belt centre distance for correct PHG belt length, and target shaft diameter + keyway so we quote either the direct-bore machining or the correct Taper Lock bush option (2012 vs 2517 typical for this PD).