Manual lover wins the auto/manual fight...(rant posting)

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Originally Posted by Brian Hjelm

Never had anything at all to do with harvesters but surprised to hear they travel them distances with hydrostatic drive. They must have super good oil cooling systems. The problems with continuous travel & hydrostatic drive were (1) keeping the stuff cool. This is a high friction drive system and heat is also generated by the forcing of the high pressure oil through the small orifices in the motors. (2) It is a relatively inefficient transmission and for travel purposes uses excessive fuel. (3) Being used for travel wears them out rapidly. The pumps and motors are expensive to rebuild. It is a very convenient, easy to use, has fine controllability, and is a highly maneuverable system. Hydrostatic transmission is what made skid steer loaders a howling success from the mid-70's on. IHC had a few farm tractors (1970's-80's) with hydraulic drive but not a success. A major application problem with torque convertor/powershift transmissions used on dozers was in land clearing, & stick raking, and ploughing where the machine operates continuously under load and overheats the transmission oil. In cyclic operation, the reverse part of the cycle is unladen and the oil temp. does not build up. Contractors in this type of work usually had direct drive (clutch) transmissions. Fiat-Allis had a magic combination of an automatic oil-filled multi-disc clutch and a powershift transmission which could be used without problems in continuous work. Pity Fiat don't make cars as good as their construction equipment.

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I think the reason they are satisfactory for highway use is that the hydrostatic system operates everything else as well and the driving wheels are only a small part of the load normally so that when on the highway the system is operating well below capacity, so cooling is adequate. The hydrostatic system is to replace the awful conglomeration of belts on older headers.

On your second point, some years ago I was looking at a tractor, partly for maintaining my roads, so I needed a blade, but it would also be used for ploughing etc. I ended up with a Chamberlain 306, with a manual transmission, but one I looked at but did not get for the reason you mention, was the same tractor with a torque converter.

John

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Originally Posted by JDNSW

I think the reason they are satisfactory for highway use is that the hydrostatic system operates everything else as well and the driving wheels are only a small part of the load normally so that when on the highway the system is operating well below capacity, so cooling is adequate. The hydrostatic system is to replace the awful conglomeration of belts on older headers.

On your second point, some years ago I was looking at a tractor, partly for maintaining my roads, so I needed a blade, but it would also be used for ploughing etc. I ended up with a Chamberlain 306, with a manual transmission, but one I looked at but did not get for the reason you mention, was the same tractor with a torque converter.

John

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You are probably right about the traction part of the system being a minor part of the hydraulic load in that type of machine. Do they travel them at a higher speed than in the paddock working? Do they leave the fronts on? I have often seen someone towing a header front on a long skinny trailer type rig down country roads but always assumed the header itself would be on a trailer also. Leaving the front bit on would severely restrict your choice of roads.

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Originally Posted by Brian Hjelm

You are probably right about the traction part of the system being a minor part of the hydraulic load in that type of machine. Do they travel them at a higher speed than in the paddock working? Do they leave the fronts on? I have often seen someone towing a header front on a long skinny trailer type rig down country roads but always assumed the header itself would be on a trailer also. Leaving the front bit on would severely restrict your choice of roads.

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They have an hydraulic system for the drive and another system to adjust the comb height and reel speed and position etc. Mine uses a belt to drive the cutter bar. The threshing mechanism is not usually hydraulically driven, rather by belts and chains, and its the threshing, seperating and straw chopping that uses the majority of the power. Paddock speed is typically 6-8kph.

It is illegal to drive a header on the road with the comb attached - all machinery must be reduced to its narrowest possible width.