Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

Dave e Victoria · 02-15-2007, 03:54 PM

Reply Two.
The two issues most likely affecting ride are bouncing and chucking. I have come to believe that bouncing issues mostly involve the suspension of the TV and trailer. If either is bottoming out there is not much one can do to solve the problem by modifying the hitch. Crawl under the loaded trailer and measure the distnce between the axle and the frame. If this distance is less than two inches you are not going to have a good ride.

Turning to chucking, this phenomenon is unique to fifth wheel geometry and does not exist on properly loaded travel trailers. (They have their own problems which are also due to geometry and are much worse.). The geometry problem for fifth wheels results from the height of the hitch point above the rear axle of the TV.. If you visualize this distance as a sort of lever you will note that anything that causes the plane of the tires to be uneven, such as the front tires of the tv going over a bump, the fixed point connetion between the TV and trailer must either push the trailer back or the TV forward. The result is a jolt in the back of the seat. The only way to address this problem is to introduce some elastic member between the inertia of the trailer and the inertia of the TV. This elasticity is what the rubber provides in the MorRyde or what the airbag and shock provide in the Air Ride.

Chucking motion translates into mostly foreaft jolts. If the hitch point is increased a lot the motion would begin to translate into up down motion in the ride. Fortunately, this is not the case in properly loaded trailers.. If we could get the hitchpoint closer to the TV axle we coul largely eliminate chucking. Infact, this is an advantage of gooseneck style hitches.

I mentioned proper loading in the last paragraph. Since there is some tendency to translate chucking motion into up down motion, a tailer that is perfectly balanced around its own axle will amplify any tendency to translate chucking into a bounce. Forward loading of the trailer will virtually eliminate this tendency. That is why trailers loaded with about 20% 0f the overall load on the pin will ride better. Of course that assumes that both trailer and TV are well within the weight rating of the suspensions.

02-15-2007, 03:54 PM	#36
Dave e Victoria Montana Master Join Date: Nov 2003 Location: Glendale Posts: 1,219 M.O.C. #635	Reply Two. The two issues most likely affecting ride are bouncing and chucking. I have come to believe that bouncing issues mostly involve the suspension of the TV and trailer. If either is bottoming out there is not much one can do to solve the problem by modifying the hitch. Crawl under the loaded trailer and measure the distnce between the axle and the frame. If this distance is less than two inches you are not going to have a good ride. Turning to chucking, this phenomenon is unique to fifth wheel geometry and does not exist on properly loaded travel trailers. (They have their own problems which are also due to geometry and are much worse.). The geometry problem for fifth wheels results from the height of the hitch point above the rear axle of the TV.. If you visualize this distance as a sort of lever you will note that anything that causes the plane of the tires to be uneven, such as the front tires of the tv going over a bump, the fixed point connetion between the TV and trailer must either push the trailer back or the TV forward. The result is a jolt in the back of the seat. The only way to address this problem is to introduce some elastic member between the inertia of the trailer and the inertia of the TV. This elasticity is what the rubber provides in the MorRyde or what the airbag and shock provide in the Air Ride. Chucking motion translates into mostly foreaft jolts. If the hitch point is increased a lot the motion would begin to translate into up down motion in the ride. Fortunately, this is not the case in properly loaded trailers.. If we could get the hitchpoint closer to the TV axle we coul largely eliminate chucking. Infact, this is an advantage of gooseneck style hitches. I mentioned proper loading in the last paragraph. Since there is some tendency to translate chucking motion into up down motion, a tailer that is perfectly balanced around its own axle will amplify any tendency to translate chucking into a bounce. Forward loading of the trailer will virtually eliminate this tendency. That is why trailers loaded with about 20% 0f the overall load on the pin will ride better. Of course that assumes that both trailer and TV are well within the weight rating of the suspensions.