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4 low or 4 high?

2K views 6 replies 5 participants last post by  StanMI 
#1 ·
I have lots of hills on my property some pretty steep sometimes I shift to 4 low on the steep ones but I seem to smell the belt.. but I've read to use 4 low for steep climbs but 4 high seems easier on the ranger? What do u guys do?
 
#5 · (Edited)
CVT systems all work pretty much the same way so no matter what machine you have little changes as far as when to use low or high. My '15 570 XP & 900 Owner's Manual says to use low under speeds of 10 MPH, when pulling loads or plowing and climbing steep grades. The belt will slip and burn if not properly warmed before being heavily loaded as well. It comes down to engagement RPM. Engagement is controlled by centrifugal force which is determined by RPM. If you are doing any of the things previously mentioned in high range the engine speed will be so low that full engagement cannot take place and the belt slips. Slippage = heat = belt burn.

In addition, on a stock CVT system, the system provides not only a change in ratios but also clutching. The clutching portion of the system is what causes the problems. To provide clutching the belt is loose at idle when you are stopped and no power is transferred to the gearbox/transmission. The primary clutch sheave halves are spread apart and the inside flat portion of the belt is riding on the flat area between the sheave halves. This flat area is not a friction surface and provides no driving force. When engine speed is increased, as you apply throttle, centrifugal force is imparted to the weights in the primary clutch and they move the sheave halves closer together and belt engagement begins. During this period there is slippage between the sides of the belt and sheave halves, which are the friction surfaces that provide driving force. Attempting smooth, slow acceleration at this point lengthens the time the slippage is taking place and increase heat and wear and can cause burning of the belt. This situation is worsened when loads are high such as when high range is used for pulling loads, climbing hills, plowing, etc. Attempting to drive slowly, less than approximately 10 MPH also causes only partial engagement and increased slippage. The belt is not moving very fast past the primary sheaves in high range at low speeds so the slippage of the sheave halves is concentrated in a small area causing belt damage.

Without intending to promote the Duraclutch, this is where the Duraclutch differs. The belt on the Duraclutch is tight at all times and does not provide the actual clutching. Clutching is provided by a second centrifugal clutch system within the Duraclutch. That second system contains shoes, somewhat like brake shoes, designed to handle the slippage, heat and wear of slippage cause by clutching engagement. The belt does not slip, therefore cannot burn.

Hopefully by better understanding how the CVT system works you will be better able to determine when to use low and when to use high ranges.
 
#6 ·
Imagine trying to pedal a 10 speed bicycle up a steep hill. You can do it in low gear, but not in high. The problem occurs when you add 50 HP to the peddler, you now have the power to break stuff. If you use the mechanical advantage that low range offers, you won't have as many problems. The other issue that you have with high range is that if you loose traction, your tires will get spinning much quicker then if you were in low range, and when you do regain traction is when you break stuff (Axles, belts, and secondaries).
 
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