A polycarbonate tractor window is replaced in a farmyard, often at harvest, and the part that decides whether the job takes an hour or a day is the seal rather than the sheet.
A contractor in Lincolnshire replaced six side windows with bonded panels. Four cracked at the bond line within a season because the cab frame flexes on rough ground and the rigid joint took the movement.
Polycarbonate tractor window gauge and seal
- Side or rear: 6 mm
- Front screen: 8 mm
- Seal: EPDM gasket with 2 mm clearance
- Cut: to the original glass profile, minus 1 mm
The gasket is the field-serviceable detail. A rubber gasket lets a window be swapped with hand tools in a yard; a bonded panel needs the cab stripped, which is why bonded repairs get deferred until the window is unusable.
Dust, spray and scratch life
Dust is the everyday abrasive. A cab window is wiped dry several times a day, and that dry wipe with field dust is what hazes a panel in a season; a water rinse before wiping doubles the clarity life.
Spray chemistry is the other variable. Most products are harmless, but solvent carriers and some adjuvants attack the surface, and a concentrated spill leaves a crazed patch that cracks under vibration.
For the windscreen version on smaller vehicles, polycarbonate windshields covers the salt-and-spray case.
Send your cab model, window profile and quantity to oversales@rpplexiglass.com for replacement pricing.
Frequently Asked Questions
What thickness polycarbonate for a tractor window?
6 mm for a side or rear window, 8 mm for a front screen that takes branch strikes. A cab front on a loader needs the thicker grade because of impact rather than wind load.
Will polycarbonate survive agricultural chemicals?
Most crop sprays are fine; solvents and some concentrated adjuvants attack it. A wash-down with water and mild detergent after spraying extends the panel life significantly.
How is the window fixed in the cab frame?
With a rubber gasket and a sealed bead, not a bonded panel. A bonded window cannot be replaced in the field, and a cab frame flexes enough to crack a rigid bond.