The CAT 320C and 320D swing gearbox<\/strong> \u2014 both catalogued under part number 148-4644<\/strong> \u2014 is one of the most frequently sourced aftermarket swing drive components for Caterpillar excavators. The PC200-6 is the Komatsu benchmark; the CAT 320 is the Caterpillar equivalent in the 20-tonne class. This guide answers the question most buyers ask first: are the 320C and 320D units actually interchangeable? It also covers serial range verification, OEM vs aftermarket evaluation, sourcing logistics, and what to inspect during installation.<\/p>\n<\/div>\n The CAT 320C and 320D are successive generations of Caterpillar’s 20-tonne crawler excavator. The 320D introduced in 2006 brought a new engine (C6.4 ACERT), updated hydraulic controls, and improved cab ergonomics \u2014 but the swing drive system retained strong dimensional continuity with the 320C.<\/p>\n For the swing gearbox specifically, part number 148-4644<\/strong> covers both models within certain serial ranges. However, “same part number” does not automatically mean every 320C and every 320D uses the same physical unit \u2014 production updates within a model generation can create dimensional or port-layout changes that the shared part number obscures.<\/p>\n \u26a0\ufe0f Bottom line on interchangeability:<\/strong> The 148-4644 swing gearbox fits both 320C and 320D machines within specified serial ranges. However, you must verify your machine’s serial prefix before ordering \u2014 not all 320C and 320D serial ranges are covered by the same specification. Send your serial prefix and model to your supplier for a 4-hour confirmation.<\/p>\n <\/p>\n <\/p>\n While the 148-4644 swing gearbox<\/strong> is primarily associated with the CAT 320C and 320D, the compatible model list extends across multiple brands and weight classes. The table below gives a representative cross-section:<\/p>\n \u2726 Primary fit.<\/strong> For non-CAT models, confirm serial prefix with your supplier before ordering. Cross-brand dimensional equivalence is common but requires individual verification.<\/p>\n <\/p>\n Whether you’re sourcing from a dealer or an aftermarket supplier, these three questions filter out poor-quality sources and prevent the most common ordering mistakes:<\/p>\n <\/p>\n The CAT 320 series swing gearbox shares the same failure modes as other 20t-class excavator swing drives, but the 320C and 320D’s swing motor architecture means some symptoms present slightly differently:<\/p>\n A noticeable lag between joystick input and upper body movement, especially at the start of a swing cycle. Early-stage planetary wear.<\/p>\n<\/div>\n<\/div>\n A repeating knock or clunk that occurs at regular intervals during slow swing. Planet gear or carrier pin wear in the second reduction stage.<\/p>\n<\/div>\n<\/div>\n Silver or grey metallic particles in the swing motor case drain oil at service. Internal gear wear is at an accelerating stage \u2014 order replacement immediately.<\/p>\n<\/div>\n<\/div>\n Visible gear oil seeping from the output shaft lip seal area. Seal failure allows dirt ingress that rapidly accelerates internal wear.<\/p>\n<\/div>\n<\/div>\n The gearbox housing is excessively hot to touch after normal operating cycles. Bearing failure or contaminated oil causing friction-generated heat build-up.<\/p>\n<\/div>\n<\/div>\n<\/div>\n <\/p>\n \ud83d\udca1 Machine-down tip:<\/strong> Processing for in-stock units is 4\u20137 business days. For true machine-down emergencies, contact your supplier at time of order and request priority processing \u2014 most in-stock units can be handed to an air freight carrier within 48\u201372 hours. Specify your urgency level in the initial enquiry so the supplier can advise the fastest available route.<\/p>\n <\/p>\n The 320C and 320D swing motor is particularly vulnerable to contamination from gearbox failure. When ordering the 148-4644 replacement, evaluate these two additional components:<\/p>\n![\"Swing](\"https:\/\/planetarygeardrive.top\/wp-content\/uploads\/2026\/03\/Gemini_Generated_Image_79mxdf79mxdf79mx-1024x687.webp\" "\\"\\"")
<\/p>\nCAT 320C vs 320D: What Changed Between Generations?<\/h2>\n
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Part Number 148-4644: Full Specification Overview<\/h2>\n
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\n \nParameter<\/th>\n Details<\/th>\n<\/tr>\n<\/thead>\n \n Part Number<\/td>\n 148-4644<\/td>\n<\/tr>\n \n Stock Code<\/td>\n 9201952<\/td>\n<\/tr>\n \n Compatible Equipment<\/td>\n CAT 320C \/ 320D Excavator (primary) \u2014 130+ models<\/td>\n<\/tr>\n \n Category<\/td>\n Construction Machinery Parts \u2014 Swing Motor Drive Reduction Gear<\/td>\n<\/tr>\n \n Application<\/td>\n Direct OEM replacement \u2014 no shimming or adaptor plates required<\/td>\n<\/tr>\n \n Condition<\/td>\n New<\/td>\n<\/tr>\n \n Quality Test<\/td>\n 100% no-load run-in + rated-torque bench test \u2014 signed report included<\/td>\n<\/tr>\n \n Warranty<\/td>\n 3 months from arrival date<\/td>\n<\/tr>\n \n MOQ<\/td>\n No minimum \u2014 emergency single-unit orders accepted<\/td>\n<\/tr>\n \n Lead Time (in stock)<\/td>\n 4\u20137 business days processing<\/td>\n<\/tr>\n \n Shipping Options<\/td>\n Sea (18\u201335 days) \/ Air freight (5\u20138 days) \/ DHL FedEx express<\/td>\n<\/tr>\n \n Trade Terms<\/td>\n EXW, FOB, CFR, CIF \u2014 Jiangmen Port, China<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n Machines Covered: 130+ Models Beyond the 320C and 320D<\/h2>\n
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\n \nBelow 10t<\/th>\n 10\u201320t<\/th>\n 20\u201330t<\/th>\n 30\u201340t<\/th>\n 40t+<\/th>\n<\/tr>\n<\/thead>\n \n E307B<\/td>\n E315<\/td>\n E320C \u2726<\/td>\n E330<\/td>\n DH420-7<\/td>\n<\/tr>\n \n E70B-7<\/td>\n EX120-5<\/td>\n E320D \u2726<\/td>\n E330C<\/td>\n CE420-6<\/td>\n<\/tr>\n \n EX60-2<\/td>\n SK135<\/td>\n E318C<\/td>\n E330D<\/td>\n EC460<\/td>\n<\/tr>\n \n ZX75 \/ ZX85<\/td>\n PC160-7<\/td>\n DH225-7<\/td>\n PC300-7<\/td>\n PC400-6\/7<\/td>\n<\/tr>\n \n SK55 \/ SK60<\/td>\n R130 \/ SH120<\/td>\n PC200-6 \/ EC210<\/td>\n SK330-8 \/ EC350<\/td>\n \u2014<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n 3 Questions to Ask Before Ordering Any CAT 320 Swing Gearbox<\/h2>\n
5 Failure Signs Specific to the CAT 320 Swing Drive<\/h2>\n
Sourcing Guide: Lead Times and Shipping Options for Canada, Australia and Europe<\/h2>\n
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\n \nDestination<\/th>\n Sea Freight<\/th>\n Air Freight<\/th>\n DHL \/ Express<\/th>\n<\/tr>\n<\/thead>\n \n Canada<\/td>\n 20\u201328 days<\/td>\n 5\u20137 days<\/td>\n 3\u20135 days<\/td>\n<\/tr>\n \n Australia<\/td>\n 18\u201325 days<\/td>\n 5\u20138 days<\/td>\n 4\u20136 days<\/td>\n<\/tr>\n \n Europe (Hamburg \/ Rotterdam)<\/td>\n 28\u201335 days<\/td>\n 5\u20138 days<\/td>\n 3\u20135 days<\/td>\n<\/tr>\n \n USA<\/td>\n 22\u201330 days<\/td>\n 5\u20137 days<\/td>\n 3\u20135 days<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n What to Replace at the Same Time as the 148-4644 Swing Gearbox<\/h2>\n