Irus Balkenmäher
1 model in this series
Irus ER (bar mower) – air-cooled single-cylinder two-stroke engine with 7.5 hp at 3,000 rpm, 500 mm cutting width, built from around 1960 to 1970.
The ER is a bar mower with a single-cylinder two-stroke engine, of a type built from around 1960 to 1970. Bar mowers of this kind were mainly used in hill and grassland farming, on ground too steep or too small for larger, wheel-driven mowing machines.
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The air-cooled single-cylinder engine of 246 cm3 displacement runs on a 1:25 petrol-oil mixture and produces 7.5 hp at 3,000 rpm. With a 500 mm working width, 2,000 mm length and 1,200 mm overall height, the ER is a compact, hand-guided machine. Its 20 km/h top speed applies to transport between work areas, not to the mowing itself.
A two-stroke engine running on a petrol-oil mixture was the common design for hand-guided bar mowers of this power class, being light, simple in construction and needing no separate oil circuit. Machines of this kind belong to the group of single-axle motor mowers that still play a role today on steep ground and specialty crops where larger vehicles cannot be used.
When buying an old bar mower, the condition of the cutter bar and the blade guide matters most: worn guide rails and loose blades noticeably reduce cutting quality. The two-stroke engine should be checked for compression and the condition of the piston rings, and the correct 1:25 mixing ratio must be observed on every restart. Drive belt and clutch lever also belong on the checklist; parts are usually only available through dealers specialising in vintage equipment.
Sources: SpecCodex-Register: Kennwerte des Modells Irus ER
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