Our new CASE IH magnum 225 cvt. 225 hp. Tractor has front suspension, and cab suspension. With four wheel braking via fwd.
Personally I wouldnt want 4 wheel braking unless it would only work when in its highest gear for road travel only. Any other time and it would be a hindrance to turning with the steering brakes. If using the brakes for turning sharply, you need the front wheels to roll not not lock up and with 4 WD you would want the front to pull you around not stop. I would just see front brakes as an unnecessary expense to maintain and a hindrance to proper operation of the tractor. Most tractors here in the states only travel 25 MPH or less in road gear and there is no need for extra braking.
Firstly tractors which are 4-wheel braking normally have electronic activation - meaning you can switch it off in field to still be able to use the independent brakes for turning.
Also having worked for a large agricultural contractor for many years in the UK, we unfortunately saw many incidents where tractors towing heavy loads / large balers etc... could have used front brakes - especially when going down slippery steep hills. Most of the accidents I've seen have actually been on the road, with tractors travelling at conventional speeds (under 25kph), but which have lost the traction on tarmac. An Ag tractor tyre doesn't have much contact with the road compared to a conventional tyre, so it is easy to loose the traction when only relying on two wheels (as oppose 4) to stop you!
Luckily I've never had an accident, but have had a few occasions when I wished I had 4-wheel braking - or automatic 4WD as has already been mentioned. :thumbsup:
There is a SAE braking standard that all self-propelled mobile equipment must meet. The standard specifies maximum stopping distance at various speeds (it is an exponential curve) at maximum vehicle load. The EC standard (European) requires brakes at all wheels even if the machine can meet the stopping distance requirement with only 2 wheel brakes. Like the person from the UK said, you will find all wheel brakes on European machines that have equivalent US models equipped with only rear brakes. In addition the Europen tractors require supplemental steering for machines that travel faster than 20 km/hr (hydrostatic power steering machines that is). So some tractors are limited to slower travel speeds on Euro models in order to avoid the expense of the supplemental steering but there is no way to get around the all wheel braking. It gets complicated for us manufacturers building equipment in European and North American plants that can shift production volumes between plants depending on demand. The cost penalty is quite large so we stock axles with and without brakes depending on where the machine is being shipped.
Our case ih has 32 mph road speed and fwd drive engages if you apply both left and right brake pedals, or in park. If only one brake is applied only that rear wheel brakes. That makes it highly important to lock the pedals together for road travel. The set up works well, like you said, For turning.Quote:
Originally Posted by Gary Fowler
Thinking about using the front wheels of a conventional FWA as complementary braking raises the question of the differential action of the FWA. (In my mind at least) We lock the two brake pedals together for road travel so that, in a panic situation, the operator doesn't depress only one pedal causing the tractor to veer in that direction. I'm just trying to visualize what happens when the FWA is engaged in this scenario but the two front wheels have unequal braking traction. Is there a potential problem at road speed?
I never had any of my tires sliding on the road. You would probably turn off the drive shaft before skidding with you front tires on a dry road. With a larger tractor that is. But on ice I guess you would get that differential action.Quote:
Originally Posted by npalen
Also there are a number of tractors which do have front braking and suspension, despite only having a 25kph transmission (for example older fendt tractors etc...). I don't know about the rest of Europe, but in the UK the requirement is not just for front brakes and suspension, but it must be a failsafe air braked system for higher speeds which maybe what you are referring to?