{"product_id":"liftmaster-71-1550b18qgh","title":"LiftMaster 71-1550B18QGH Drive Sprocket — 18 Teeth, #50 Chain, 1-1\/4-Inch Bore","description":"\u003cp\u003e\u003cstrong\u003eThe LiftMaster 71-1550B18QGH is an 18-tooth drive sprocket for #50 roller chain, with a 1-1\/4-inch bore and a 1\/4-inch keyway. It is a replacement mechanical drive component for an assembly that specifies this exact sprocket configuration. Match the complete part number, shaft size and original drive arrangement before ordering. Tooth count and bore size both matter: a sprocket that accepts the same chain can still have the wrong shaft fit or alter the original drive ratio.\u003c\/strong\u003e\u003c\/p\u003e\u003ch2\u003eCompatibility — Models, Versions and Exclusions\u003c\/h2\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eModel or selection point\u003c\/th\u003e\n\u003cth\u003eCompatibility requirement\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eExact documented replacement\u003c\/td\u003e\n\u003ctd\u003eUse where the equipment parts list specifies this complete reference or an approved equivalent.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e#50 chain\u003c\/td\u003e\n\u003ctd\u003eCorrect chain family, but chain size alone does not establish operator or shaft compatibility.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOther 1-inch-bore sprockets\u003c\/td\u003e\n\u003ctd\u003eA smaller bore does not fit the specified 1-1\/4-inch shaft; matching chain family and tooth count cannot correct that difference.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOther tooth counts or bore sizes\u003c\/td\u003e\n\u003ctd\u003eDo not substitute without approval for the complete drive assembly.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch2\u003eMatch Shaft Fit and Drive Geometry\u003c\/h2\u003e\u003cp\u003eThis QGH version has the larger 1-1\/4-inch bore. The 18-tooth LGH version uses a 1-inch bore, while the 32-tooth QGH version shares the larger bore but changes tooth count. Neither is established as a substitute for this exact configuration. Keep both dimensions visible when ordering, especially if an old invoice abbreviates the part number or describes only the chain size.\u003c\/p\u003e\u003cp\u003eThe sprocket must sit in the correct chain line and be secured by the specified shaft, key and retention arrangement. Have the technician inspect the shaft and keyway for wear as well as the teeth. A damaged shaft, loose mounting or misaligned chain can cause recurring trouble after a new sprocket is installed. Photograph the existing assembly before parts are removed so its position and neighboring components can be identified.\u003c\/p\u003e\u003ch2\u003eSpecifications and Product Identification\u003c\/h2\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eDetails\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eManufacturer part number\u003c\/td\u003e\n\u003ctd\u003e71-1550B18QGH\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSprocket designation\u003c\/td\u003e\n\u003ctd\u003e50B18\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTooth count\u003c\/td\u003e\n\u003ctd\u003e18\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChain family\u003c\/td\u003e\n\u003ctd\u003e#50 roller chain\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBore diameter\u003c\/td\u003e\n\u003ctd\u003e1-1\/4 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eKeyway\u003c\/td\u003e\n\u003ctd\u003e1\/4 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRetention\u003c\/td\u003e\n\u003ctd\u003eManufacturer description specifies set screws; confirm supplied hardware\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003ch2\u003eBefore Ordering\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eRecord the complete operator model and the sprocket part number from its service diagram.\u003c\/li\u003e\n\u003cli\u003eConfirm 18 teeth, #50 chain, a 1-1\/4-inch shaft fit and the specified keyway.\u003c\/li\u003e\n\u003cli\u003eCheck hub clearance, chain alignment and the required shaft-retention arrangement.\u003c\/li\u003e\n\u003cli\u003eInspect the chain, connecting link, mating sprockets and shaft for related wear.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003ePackage Contents and Separate Requirements\u003c\/h2\u003e\u003cp\u003eThis listing identifies the sprocket. Do not assume that roller chain, a connecting link, shaft key, shaft or every mounting fastener is included. Verify the current supplier package and obtain the separate components needed for the repair. The set-screw reference is a retention detail; it should not be interpreted as a stainless-steel material specification or a corrosion-resistance guarantee.\u003c\/p\u003e\u003ch2 class=\"safety-warning\"\u003eSafety Warnings — Read Before Installation or Service\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eWARNING: An exposed chain drive can trap fingers or clothing and cause serious injury. Replacement requires a qualified door- or gate-systems technician.\u003c\/li\u003e\n\u003cli\u003eIsolate and secure all applicable power sources and prevent unexpected movement before working on the chain drive.\u003c\/li\u003e\n\u003cli\u003eDo not change tooth count, enlarge the bore or improvise the shaft connection to make an unmatched part fit.\u003c\/li\u003e\n\u003cli\u003eRestore guards, verify chain alignment and complete the equipment’s prescribed operating and safety tests before returning it to service.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRelated Products and Important Differences\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/garage-doorparts.com\/products\/roller-chain-10-50-chain\"\u003e#50 roller chain, 10-foot length\u003c\/a\u003e — a chain-family match; determine the required length and installation suitability.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/garage-doorparts.com\/products\/master-link-50-chain\"\u003e#50 chain master link\u003c\/a\u003e — select the correct connecting link for the actual chain; not interchangeable with a #41 link.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/garage-doorparts.com\/products\/liftmaster-50-chain-32-tooth-sprocket-1-14-bore-14-keyway\"\u003e71-1550B32QGH 32-tooth sprocket with 1-1\/4-inch bore\u003c\/a\u003e — a different tooth-count comparison, not an approved replacement for this 18-tooth sprocket.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003ch3\u003eWill any #50 sprocket fit?\u003c\/h3\u003e\u003cp\u003eNo. Chain size, tooth count, bore, keyway, hub clearance and the approved drive arrangement must all match.\u003c\/p\u003e\u003ch3\u003eCan I change tooth count to make the opening move faster?\u003c\/h3\u003e\u003cp\u003eDo not use a service replacement to change operating speed. Any ratio change requires approval for the complete equipment and its safety system.\u003c\/p\u003e\u003ch3\u003eShould I inspect the chain at the same time?\u003c\/h3\u003e\u003cp\u003eYes. A technician should evaluate wear, alignment and the mating components so a worn chain does not undermine the repair.\u003c\/p\u003e\u003ch3\u003eDoes this listing include a shaft key and new chain?\u003c\/h3\u003e\u003cp\u003eThese are not promised as included. Confirm the supplied contents and order the separately required parts for the documented repair.\u003c\/p\u003e\u003ch2\u003eNeed Help Confirming the Right Product?\u003c\/h2\u003e\u003cp\u003e\u003ca href=\"https:\/\/garage-doorparts.com\/pages\/contact\"\u003eContact Garage-DoorParts.com before ordering\u003c\/a\u003e. Send the full equipment model, readable part labels and photographs of the installed assembly. Include the dimensions, electrical configuration or accessory details relevant to your project so the listing can be checked against the actual installation.\u003c\/p\u003e","brand":"Controlled products","offers":[{"title":"Default Title","offer_id":60655783215390,"sku":"71-1550B18QGH","price":45.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0978\/2781\/5710\/files\/71-1550b18qgh-pngqgh.png?v=1793139967","url":"https:\/\/garage-doorparts.com\/products\/liftmaster-71-1550b18qgh","provider":"garage-doorparts.com","version":"1.0","type":"link"}