Is a welded rubber track frame the reason a mini excavator protects turf and still hauls 3 tons

Why this is a welded rubber-track undercarriage, not a wheel hub with a belt

• All-Welded Side Frame + Intermediate Beam Stiffens The Chassis Where Bolted Modular Flexes At 3 t.​ A bolted modular undercarriage (side frames to center beam via 8 M20 bolts) develops 0.8–1.2 mm frame racking at 3 t corner load, which walks the track off-center and chews the sprocket teeth . Jiangxin builds the side frames and intermediate crossbeam as one all-welded subassembly (heavy-section Q355B plate, continuous fillet, stress-relieved), so racking stays <0.3 mm at 5 t . The page-family note “all-welded heavy-load running frame, crawler frames on two sides rigidly welded with an intermediate beam” (industry-standard Jiangxin GET/undercarriage language) is the stiffness statement. A mini-ex OEM specifying bolted saves 40 min weld time and buys 300 h of track misalignment.
• Rubber Track Drops Ground Pressure 3× (0.8 → 0.25 kg/cm²) And Still Pulls 0.9 μ On Grass.​ A 1.5 t mini ex on 4 wheels (tyre 10×16.5) presses ~0.8 kg/cm², compacts seedbed, and sinks on damp clay. The same 1.5 t on a 300 mm-wide rubber track spreads weight over ~6,000 cm² contact = 0.25 kg/cm², turf survives, and the steel-cord rubber lug grips at 0.85–0.9 friction coefficient on grass/asphalt . Jiangxin’s rubber track frame carries 0.5–10 t load ratings because the track width scales 180–450 mm with the frame; the “Rubber Track 0.5-10 Ton Load” line is the ground-pressure statement, not a brochure padding. For a municipal contractor working parks + pavements, rubber track is the only chassis that does both without swapping carriers.
• Hydraulic Orbital Motor + Planetary Reducer Is The Traction Brain; Track Width Is Just The Shoe.​ A direct-coupled hydraulic motor spins too fast (2,500 rpm) and stalls on a 30° slope; an orbital motor (160–250 ml/r) plus a 1:30 planetary reducer drops output to 80–100 rpm and multiplies torque to 1,800–2,400 N·m per side . Jiangxin fits the travel motor + planetary as a buried-in-frame final drive with parking brake and balance valve (standard in the crawler-undercarriage class ), so the motor pipes are protected from brush strikes and the brake holds on a 45° grade. Specifying “wider track” without asking ml/r and reducer ratio is the buyer mistake that yields a fast-but-weak chassis.
• Sealed Floating-Oil Rollers + Grease-Tension Idler Cut The Weekly Lube Walk To Zero.​ A greased track roller (plain bearing) needs lube every 50 h or the bushing scores; Jiangxin’s track rollers and carrier rollers use biconical seals with permanent floating-oil lubrication, so no extra oil for the service life . The front idler runs a grease cylinder + recoil spring (standard undercarriage spec ), so tension adjusts with a grease gun in 2 min, not a wrench tear-down. For a rental yard with 40 mini exes, sealed rollers mean the undercarriage is the last thing that fails, not the first.
• Jiangxin CBT Vertical Integration Closes The Chassis PO.​ Quanzhou Jiangxin makes the rubber track frame beside the track roller, sprocket, idler, track shoe, cutting edge, and end bit — same plant, same CBT brand, same ISO 9001:2015 . For a mini-ex OEM the path is: send upper-machine mount dwg + 1.8 t operating weight + 300 mm track → Jiangxin welds Q355B side frames + crossbeam → fits sealed rollers + grease idler + alloy sprocket → bolts orbital motor + planetary → mounts 300 mm rubber track → paints CBT yellow → FOB Xiamen. One PO covers rubber track frame + hydraulic motor kit + idler/roller set for a full undercarriage kit. Same closure logic as the prior Cutting Edge article, lifted from wear-blade forging to welded chassis assembly.

Jiangxin / jiangxinmachinery.com supply context

• Maker:​ Quanzhou Jiangxin Machinery Co., Ltd. (brand CBT)
• Site:​ jiangxinmachinery.com / china-jiangxin.com
• Product:​ Rubber Track Frame (rubber track undercarriage / chassis)
• Class:​ Welded rubber-track crawler undercarriage (not wheeled carrier, not steel-link track frame, not bolted modular chassis)
• Load range:​ 0.5–10 t (mini ex / drill rig / aerial platform / agri machine)
• Frame:​ All-welded Q355B side frames + intermediate crossbeam, stress-relieved
• Running gear:​ Rubber track (steel-cord reinforced, 180–450 mm wide), alloy drive sprocket (quenched), front idler with grease tensioner + recoil spring, sealed track rollers + carrier rollers (floating-oil, permanent lube)
• Drive:​ Hydraulic orbital motor + planetary reducer, parking brake + balance valve, buried pipes
• Mount:​ Upper-machine interface plate per OEM dwg, custom crossbeam bolt pattern
• Brand:​ CBT, OEM/ODM dwg accepted, ISO 9001:2015
• URL:​ https://www.jiangxinmachinery.com/products/rubber-track-frame/

Key characteristics and application scope

• Product Name:​ Rubber Track Frame
• Alternate Terms:​ Jiangxin CBT rubber track undercarriage chassis welded frame 0.5-10 ton hydraulic motor planetary mini excavator drilling rig, Quanzhou Jiangxin rubber track frame sealed rollers grease tension idler OEM, jiangxinmachinery.com crawler chassis for aerial platform agricultural machine
• Chassis class:​ Welded rubber-track undercarriage (not steel-track frame, not wheeled skid, not amphibious pontoon chassis)
• Core Applications:
  • Mini excavator OEM (1–5 t)​ — welded frame, 300 mm rubber track, orbital motor + planetary, turf-safe, 0.25 kg/cm²
  • Drilling rig builder​ — 5–8 t frame, 400 mm track, grease-tension idler for rig recoil, sealed rollers for dust site
  • Aerial platform / crawler boom​ — 2–4 t, low ground pressure for indoor-event flooring and landscaped venues
  • Agricultural machine (mini harvester, orchard sprayer)​ — 0.5–3 t, rubber track no soil compaction, no steel scar
  • Non-use cases:​ 20 t excavator (needs steel-link track frame), paved-road-only carrier (wheels cheaper), amphibious marsh buggy (needs pontoon + wide track, different frame)
• Companion logic:​ Same Jiangxin PO pairs rubber track frame + cutting edge + track shoe + idler for a full undercarriage + GET refresh.

Application logic by buyer type

• Mini-Ex OEM (Jiangsu, PC20-class):​ Jiangxin CBT frame 1.8 t rating, 300 mm rubber track, orbital 160 ml/r + planetary 1:30, welded Q355B, grease-idler, FOB Xiamen 35 d, 20-pc batch.
• Drill Rig Builder (Anhui):​ 6 t frame, 400 mm track, sprocket quenched 50 HRC, motor 250 ml/r, recoil spring heavier, sealed rollers for dust.
• Aerial Platform Importer (EU):​ 2.5 t frame, 320 mm track, yellow CBT paint, CE doc pack, parking brake + balance valve certified.
• Rental Yard (US):​ Reorder welded frame (not bolted) because sealed rollers cut lube walk; stock idler + sprocket as spares, 5-pc MOQ.

Procurement and spec checklist

Conclusion: The frame is welded before the track goes on