{"product_id":"4-5-module-spur-gear-pinion-gears-10t-to-20t-metal-spur-transmission-steel-45","title":"4-5 Module Spur Gear Pinion Gears 10T to 20T Metal Spur Transmission Steel #45","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003e4-5 Module Spur Gear Pinion — Reliable Steel Transmission for Demanding Drive Systems\u003c\/h2\u003e\n\u003cp\u003eWhen a stripped or undersized pinion gear causes your drive train to slip, skip, or fail mid-operation, the cost goes beyond the part itself. Whether you are building a CNC router, a robotic arm, an automated conveyor, or a custom power transmission assembly, you need a spur gear pinion that holds its tooth profile under load. These Module 4 and Module 5 steel spur gear pinions are engineered for makers, machinists, and engineers who cannot afford imprecise meshing or premature wear.\u003c\/p\u003e\n\u003cp\u003eEach pinion gear is machined from Steel #45 (medium carbon steel), a material known for its balanced hardness and toughness. The Module 4 pinions span 10 to 20 teeth, with an outer diameter ranging from approximately 48 mm (1.89 in) for the 10T up to approximately 88 mm (3.46 in) for the 20T. The Module 5 pinions are available in 10T and 11T, with outer diameters of approximately 60 mm (2.36 in) and 65 mm (2.56 in) respectively. Bore diameter and keyway dimensions vary by tooth count — see variant options for exact bore specifications.\u003c\/p\u003e\n\u003cp\u003eThese spur gear pinions suit a wide range of applications: precision axis drives in CNC milling machines and laser cutters, gear reduction stages in robotics and automation rigs, and replacement transmission components in industrial machinery. The involute tooth profile ensures smooth engagement with matching module rack or gear, making them a dependable choice for both prototype builds and production-line equipment.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-compat\"\u003e\n\u003cspan class=\"hdiy-compat-icon\"\u003e⚙️\u003c\/span\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Designed to mesh with Module 4 or Module 5 spur gears and racks sharing the same module and pressure angle (typically 20°). Verify bore diameter and keyway dimensions against your shaft before ordering.\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These Module 4-5 Spur Gear Pinions\u003c\/h2\u003e\n\u003cdiv class=\"hdiy-list\"\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\n\u003cstrong\u003eSteel #45 Construction\u003c\/strong\u003e\n\u003cp\u003eMachined from medium carbon Steel #45 for a strong balance of hardness, toughness, and machinability — resists deformation under sustained torque loads.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\n\u003cstrong\u003eWide Tooth Count Range\u003c\/strong\u003e\n\u003cp\u003eModule 4 available in 10T through 20T; Module 5 in 10T and 11T — covering a broad range of gear ratio and torque requirements in a single product line.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🎯\u003c\/span\u003e\n\u003cstrong\u003eInvolute Tooth Profile\u003c\/strong\u003e\n\u003cp\u003eStandard involute geometry ensures smooth, low-noise meshing with compatible module racks and gears, reducing vibration in high-cycle drive applications.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\n\u003cstrong\u003eConsistent Module Pitch\u003c\/strong\u003e\n\u003cp\u003eStrict module tolerance (4M or 5M) guarantees correct center distance and backlash when paired with matching module components in your drivetrain.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛡️\u003c\/span\u003e\n\u003cstrong\u003eCorrosion-Resistant Surface\u003c\/strong\u003e\n\u003cp\u003eNatural steel finish with inherent oxide layer; suitable for indoor mechanical environments. Apply grease or anti-rust coating for extended service life in humid conditions.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔧\u003c\/span\u003e\n\u003cstrong\u003eDirect Shaft Mounting\u003c\/strong\u003e\n\u003cp\u003ePre-bored center hole designed for shaft insertion; compatible with standard keyway and set-screw retention methods for secure, concentric mounting.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — Spur Gear Pinion\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eSteel #45 (Medium Carbon Steel)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eModule\u003c\/th\u003e\n\u003ctd\u003e4M \/ 5M\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTooth Count\u003c\/th\u003e\n\u003ctd\u003e10T – 20T (4M); 10T – 11T (5M)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePressure Angle\u003c\/th\u003e\n\u003ctd\u003e20°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter (4M 10T)\u003c\/th\u003e\n\u003ctd\u003eApprox. 48 mm (1.89 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter (4M 20T)\u003c\/th\u003e\n\u003ctd\u003eApprox. 88 mm (3.46 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOuter Diameter (5M 10T)\u003c\/th\u003e\n\u003ctd\u003eApprox. 60 mm (2.36 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBore Diameter\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHub Width\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eKeyway\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish\u003c\/th\u003e\n\u003ctd\u003eNatural steel (uncoated)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eQuantity\u003c\/th\u003e\n\u003ctd\u003e1 Pcs per order (default)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-faq\"\u003e\n\u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I choose between Module 4 and Module 5?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eModule number defines the tooth size and pitch. A higher module means larger, stronger teeth capable of transmitting more torque. Choose Module 4 for lighter-duty or space-constrained drives; choose Module 5 when your application demands higher load capacity or you are replacing an existing 5M component. Always match the module of the pinion to the module of the mating gear or rack.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat tooth count should I select for my gear ratio?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eGear ratio is determined by dividing the number of teeth on the driven gear by the number of teeth on the driving pinion. For example, pairing a 4M 10T pinion with a 4M 40T gear gives a 4:1 reduction. Select the tooth count that achieves your target ratio while keeping center distance within your design envelope.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre these pinions compatible with my existing rack or gear?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThese pinions will mesh correctly with any spur gear or rack that shares the same module (4M or 5M) and the same pressure angle (20°). Metric module gears are not interchangeable with imperial diametral pitch (DP) gears even if the tooth count matches. Verify both module and pressure angle before ordering.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow strong are Steel #45 spur gears under load?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eSteel #45 has a tensile strength of approximately 600–800 MPa in its normalized state, making it significantly stronger than brass or cast iron alternatives. It handles moderate-to-high torque in continuous-duty applications. For extreme shock loads or very high RPM, consider whether additional surface hardening treatment is appropriate for your use case.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo these gears require lubrication?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eYes. Like all steel spur gears, these pinions perform best and last longer when lubricated with a suitable gear grease or oil. Apply lubricant to the tooth flanks during installation and re-lubricate at regular maintenance intervals based on your duty cycle and operating environment.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat bore diameter does each variant have?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eBore diameter varies by module and tooth count. Please refer to the variant options or contact us to confirm the exact bore size for your selected module-teeth combination before ordering, especially if you need to match a specific shaft diameter.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use these pinions in outdoor or humid environments?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\u003cp\u003eThese gears have a natural steel finish without a protective coating. For outdoor or high-humidity environments, we recommend applying a corrosion-inhibiting grease or anti-rust spray to the tooth surfaces and bore. For permanently wet or corrosive environments, consider stainless steel alternatives.\u003c\/p\u003e\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"hdiy-cta\"\u003e\n🛒 Select your Module - Teeth combination above, then add to cart.\n\u003c\/div\u003e\n\n\u003c\/div\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How do I choose between Module 4 and Module 5?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Module number defines the tooth size and pitch. A higher module means larger, stronger teeth capable of transmitting more torque. Choose Module 4 for lighter-duty or space-constrained drives; choose Module 5 when your application demands higher load capacity or you are replacing an existing 5M component. Always match the module of the pinion to the module of the mating gear or rack.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What tooth count should I select for my gear ratio?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Gear ratio is determined by dividing the number of teeth on the driven gear by the number of teeth on the driving pinion. For example, pairing a 4M 10T pinion with a 4M 40T gear gives a 4:1 reduction. Select the tooth count that achieves your target ratio while keeping center distance within your design envelope.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Are these pinions compatible with my existing rack or gear?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"These pinions will mesh correctly with any spur gear or rack that shares the same module (4M or 5M) and the same pressure angle (20°). Metric module gears are not interchangeable with imperial diametral pitch (DP) gears even if the tooth count matches. Verify both module and pressure angle before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"How strong are Steel #45 spur gears under load?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Steel #45 has a tensile strength of approximately 600–800 MPa in its normalized state, making it significantly stronger than brass or cast iron alternatives. It handles moderate-to-high torque in continuous-duty applications.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Do these gears require lubrication?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. Like all steel spur gears, these pinions perform best and last longer when lubricated with a suitable gear grease or oil. Apply lubricant to the tooth flanks during installation and re-lubricate at regular maintenance intervals.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What bore diameter does each variant have?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Bore diameter varies by module and tooth count. Please refer to the variant options or contact us to confirm the exact bore size for your selected module-teeth combination before ordering.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can I use these pinions in outdoor or humid environments?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"These gears have a natural steel finish without a protective coating. For outdoor or high-humidity environments, apply a corrosion-inhibiting grease or anti-rust spray. For permanently wet or corrosive environments, consider stainless steel alternatives.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"HomeDIYer","offers":[{"title":"4M 10T \/ 1 Pcs","offer_id":52442364838162,"sku":"FAS058241x1","price":39.55,"currency_code":"USD","in_stock":true},{"title":"4M 11T \/ 1 Pcs","offer_id":52442364870930,"sku":"FAS058242x1","price":43.64,"currency_code":"USD","in_stock":true},{"title":"4M 12T \/ 1 Pcs","offer_id":52442364903698,"sku":"FAS058243x1","price":59.36,"currency_code":"USD","in_stock":true},{"title":"4M 13T \/ 1 Pcs","offer_id":52442364936466,"sku":"FAS058244x1","price":67.82,"currency_code":"USD","in_stock":true},{"title":"4M 14T \/ 1 Pcs","offer_id":52442364969234,"sku":"FAS058245x1","price":86.92,"currency_code":"USD","in_stock":true},{"title":"4M 15T \/ 1 Pcs","offer_id":52442365002002,"sku":"FAS058246x1","price":96.42,"currency_code":"USD","in_stock":true},{"title":"4M 16T \/ 1 Pcs","offer_id":52442365034770,"sku":"FAS058247x1","price":104.92,"currency_code":"USD","in_stock":true},{"title":"4M 17T \/ 1 Pcs","offer_id":52442365067538,"sku":"FAS058248x1","price":114.72,"currency_code":"USD","in_stock":true},{"title":"4M 18T \/ 1 Pcs","offer_id":52442365100306,"sku":"FAS058249x1","price":143.32,"currency_code":"USD","in_stock":true},{"title":"4M 19T \/ 1 Pcs","offer_id":52442365133074,"sku":"FAS058250x1","price":160.13,"currency_code":"USD","in_stock":true},{"title":"4M 20T \/ 1 Pcs","offer_id":52442365165842,"sku":"FAS058251x1","price":157.94,"currency_code":"USD","in_stock":true},{"title":"5M 10T \/ 1 Pcs","offer_id":52442365198610,"sku":"FAS058301x1","price":131.96,"currency_code":"USD","in_stock":true},{"title":"5M 11T \/ 1 Pcs","offer_id":52442365231378,"sku":"FAS058302x1","price":143.89,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0884\/8936\/1682\/files\/Main-01_b18fba81-c77d-4e1c-a6d4-f9f2a5c8e40c.jpg?v=1783493465","url":"https:\/\/homediyer.com\/products\/4-5-module-spur-gear-pinion-gears-10t-to-20t-metal-spur-transmission-steel-45","provider":"HomeDIYer","version":"1.0","type":"link"}