Telehandlers are machinery that are meant to work in rough environment, although, that doesn't mean that they could be driven without any consideration for the terrain. These kinds of machinery have a much greater risk of tipping over or load loss when they are traveling on slopes.
When traveling on a slope, make certain that you move slowly with the machinery while also keeping the load low. Downshift to 4WD and a lower gear, before getting on the slope. Utilizing the engine brake would actually help to control the speed of the telehandlers. Try not to turn on a slope if possible. If you have to make the turn, take it as wide as possible and utilize extreme care.
Under any conditions, do not drive across very steep slopes. Ascend and descend slopes with the telehandler's heavy end pointing up the incline. Even when there is no cargo on the forks, the machine's counterweighted rear is fairly heavy; thus, it could be required to drive in reverse up slopes. Once the telehandler is carrying a cargo, the front of the unit becomes the heavy end, and you could back the equipment down the slopes.
Operator training is extremely vital on a mixed jobsite. Rear pivot machinery will often operate on the same jobsite of coordinated steering machines, where everyone is permitted to operate all of the equipment. In this case, a person who is used to using a coordinated steer equipment could jump onto a rear-pivot machine. A very significant difference between how these two units work depends on which part of the equipment extends outside of the turning radius.