Bushings for agricultural machinery
Farm machinery is the hardest test of a cheap bearing: dust, mud, fertiliser, water, seasonal use with long idle periods, and pivots that are greased when someone remembers. The bushings that survive are the ones that expect that.
- 120 N/mm²Wrapped bronze, static
- −195…+280 °CPTFE composite, dry
- 50–100 N/mm²Graphite bronze, no grease
- 250 N/mm²Hardened steel hitch pins
Agricultural pivots are slow, oscillating, moderately loaded, abrasive and irregularly maintained. Wrapped CuSn8 bronze bushings with grease pockets are the volume standard for linkages and implement pivots; PTFE and POM composite bushings remove the grease point on lighter joints; graphite-plugged bronze suits heavy joints that will never be greased; hardened steel is for the loader and hitch pins that see shock. Corrosion protection and seals matter as much as the bearing material.
- Three-point hitch, loader and drawbar pins: hardened steel or bimetal, greased, with seals
- Plough, cultivator, disc and harrow pivots: wrapped bronze (120 N/mm² static) or graphite bronze where greasing is impossible
- Header, reel, auger and conveyor pivots on harvesters: PTFE composite, dry, no grease points, −195 to +280 °C
- Baler, sprayer boom and folding-frame linkages: POM composite greased at assembly; plastic bushings on light links
- Fertiliser and chemical exposure: stainless or bronze backs, plated steel, dezincification-resistant alloys
Bushings for agricultural machinery
Wrapped bronze where there is a grease nipple, composite where there is not, graphite bronze on the heavy joints nobody reaches, hardened steel on the pins that take shock.
Wrapped bronze bushings
CuSn8 with grease pockets: linkage, implement and header pivots in volume.
JBM-090
PTFE composite bushings
Dry running from −195 to +280 °C: reel, auger and conveyor pivots without grease points.
JBM-10
POM composite bushings
Greased once at assembly: baler, sprayer boom and folding-frame linkages.
JBM-20
Graphite bronze bushings
Heavy, slow pivots on ploughs and cultivators that will never be greased.
JBM-650
The agricultural duty
Loads are moderate compared with construction machinery but the environment is worse: soil is an abrasive, fertiliser and manure are corrosive, machines stand idle for months and then run day and night for weeks. Greased bronze bushings work when greased; the failure mode of most farm pivots is not overload but a dry, dirty bearing. The design response is either to make the bushing hold its own lubricant (pockets, plugs, PTFE) or to seal it and grease it on a schedule the operator will keep.
| Joint | Duty | Usual bushing | Why |
|---|---|---|---|
| Three-point linkage, lift arms, top link | Oscillating, high load, shock, greased | Hardened steel or bimetal | Load and shock; grease points exist |
| Front loader pivots | Oscillating, high load, dirt | Hardened steel | Shock and grit; pins are hardened |
| Plough, cultivator, disc gang pivots | Slow, moderate load, soil | Wrapped CuSn8 bronze, pockets | Cheap, 120 N/mm² static, holds grease |
| Pivots never greased (frames, wheels, depth control) | Slow, moderate, no service | Graphite-plugged bronze | Plugs lubricate for life; dirt tolerant |
| Harvester header, reel, auger, conveyor pivots | Oscillating / rotating, moderate, dusty | PTFE composite | Dry, no grease points, crop dust does not stick |
| Baler, sprayer boom, folding frame links | Oscillating, light–moderate | POM composite, greased once | Edge loads, chemicals, low cost |
| Light linkages, guards, seats | Light | Solid plastic or sintered bronze | Corrosion-free, quiet, cheap |
Materials that survive it
Wrapped bronze (JBM-090) is the backbone of implement pivots: a 1–2.5 mm CuSn8 wall at 110–150 HB carries 120 N/mm² static and 40 N/mm² dynamic, the diamond pockets hold grease between seasons, and the part costs little in the volumes implements are built in. Where a grease point is available but rarely used, the through-hole type JBM-092 lets a single greasing reach the bore.
PTFE composite (JBM-10) removes the grease point altogether on harvester and sprayer joints where load is moderate; it runs dry from −195 to +280 °C and crop dust does not build up on a dry bearing. POM composite (JBM-20) is the choice for edge-loaded folding-frame and boom links greased once at assembly. Graphite-plugged bronze takes the heavy pivots nobody will ever grease. Hardened steel bushings and hardened pins take the hitch and loader joints where shock loads govern.
Corrosion protection is part of the specification: plated steel backs, bronze or stainless backs where fertiliser and manure are present, dezincification-resistant alloys for any brass parts, and seals or dust caps on every greased joint.
Design notes
Give agricultural pivots generous clearance (dirt needs somewhere to go and paint and rust build up), seal them where possible, and keep grease points to the ones an operator can reach from the ground. Specify the pin: an unhardened pin in a wrapped bronze bushing wears the pin first. For long idle periods choose materials that do not depend on a grease film being present at start-up: pockets, plugs or PTFE.
What to put in the enquiry
Pin diameter and hardness, housing bore, length, load or implement type, whether the joint is greased, exposure to chemicals, and annual quantity. Implement builders normally send the drawing; we quote against it within 12 hours. Samples are free.
Frequently asked questions
Which bushings are used on tractors and implements?
Hardened steel and bimetal on hitch and loader pins; wrapped bronze on implement pivots; PTFE and POM composite where grease points are eliminated; graphite bronze on heavy pivots that are never greased; plastic and sintered bronze on light links.
How do I stop farm-machinery bushings wearing out?
Choose a bushing that holds its own lubricant (pockets, plugs, PTFE), seal it, specify a hardened pin, and allow enough clearance for dirt. Most failures are dry, dirty bearings rather than overloaded ones.
Can bushings run dry on a combine header?
Yes: PTFE composite bushings run dry across the header temperature range and do not attract dust. They suit oscillating and slow rotating joints at moderate load.
What about fertiliser corrosion?
Use plated steel backs, or bronze or stainless backs on composite bushings, dezincification-resistant brass or bronze for solid parts, and seal the joint. State the chemical exposure on the enquiry.
Do you supply implement manufacturers in volume?
Yes. Wrapped bronze and composite bushings are formed on automated lines; drawings are held on file and repeat orders are scheduled. Samples of new parts are free.
Send the joint, not just the part.
Pin diameter, load, motion, lubrication and environment: our engineers reply within 12 hours with a material, a size and a quotation. Free samples, no minimum order.