a few years back, i owned a body shop that was on a state route, at times scraper parades went by! it was two lane highway at 45-mph.those scrapers, mostly green! went by hoppin up and down so much! to this day,im convinced there's no way those big tires are really round! they are egg shape!
-
Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!
scraper bounce
- Thread starter counter
- Start date
alan627b
Senior Member
On most of the large rubber tired equipment, the tires themselves are
the suspension. The casings have to be able to flex to do their job. Once they start bouncing (loping), the only way to get them to stop is to slow down. That is partly why scrapers now have cushion hitches (Cat) or suspended axles on nitrogen cushioned struts (Terex, Komatsu, Deere) or have simply gone out of business.
Some of these features have been adapted to the hydraulics on rubber tired loaders too as a means of ride control.
I shudder to think what a scraper on solid tires would be like!
And flat spotted tires are their own nightmare, although they will usually go round once they get some heat in them.
Good observation!
alan627b
the suspension. The casings have to be able to flex to do their job. Once they start bouncing (loping), the only way to get them to stop is to slow down. That is partly why scrapers now have cushion hitches (Cat) or suspended axles on nitrogen cushioned struts (Terex, Komatsu, Deere) or have simply gone out of business.
Some of these features have been adapted to the hydraulics on rubber tired loaders too as a means of ride control.
I shudder to think what a scraper on solid tires would be like!
And flat spotted tires are their own nightmare, although they will usually go round once they get some heat in them.
Good observation!
alan627b
BrianHay
Senior Member
Slow down is the only way to stop the bounce that I know of as well. Don't hit the brakes or retarder though, just drop the throttle (or throttles) long enough that when you hit them again they will be pulling. Even if your still bouncing when you hit the throttles again as long as you have slowed down enough the engines are working to get you back up to speed more often then not the bouncing will stop. For how long who knows....could be seconds, minutes or the rest of your trip.
Some machines seem to bounce at a certain speed or even engine rpm for whatever reasons, there could be countless. But if you' re on a long road trip and use the above methods after a few times bouncing and leveling it out again you will find the comfort zone where it is as fast as you can go without bouncing. Then flip the throttle lock (if ya got it) and enjoy the ride.
If you find the sweet spot and it's a big parade there will *almost* always be a hotshot or gung hoe rookie out in front or trying to pass....let em go. He will jump out in front, then start bouncing, slow down, you will catch em and often he will get in your way as your holding a steady comfortable pace. Your pace is not only comfy but will save ?$$$? in fuel.
Some machines seem to bounce at a certain speed or even engine rpm for whatever reasons, there could be countless. But if you' re on a long road trip and use the above methods after a few times bouncing and leveling it out again you will find the comfort zone where it is as fast as you can go without bouncing. Then flip the throttle lock (if ya got it) and enjoy the ride.
If you find the sweet spot and it's a big parade there will *almost* always be a hotshot or gung hoe rookie out in front or trying to pass....let em go. He will jump out in front, then start bouncing, slow down, you will catch em and often he will get in your way as your holding a steady comfortable pace. Your pace is not only comfy but will save ?$$$? in fuel.
Last edited:
Soldati06
Member
yea that bounce in the old scrapper is sometimes harmfull im in the us army and we had a guy go to the hospital because of his kidneys and supposfully he had internal bleeding gotta be carefull on those but i love them 
Hollywood627G
Active Member
i dont know about ya'll, but i speed up when it starts bouncing. Have you ever driven down a washboad road or rouh road in your car? the slower you go the more bumps you feel, and by slowing down you are still bouncing. Speeding up smooths out the ride. And also i was told that i would break before the machine does, which actually happened the opposite way since ive broke a 627 in two.
the bounce
im not an operator, but if im going to fly over speed bumps, or ,walk over them, i guess id walk, and give my truck a break!with heavy equipment maybe its expected to run full tilt to get the job done! any owner operators to help me here?
im not an operator, but if im going to fly over speed bumps, or ,walk over them, i guess id walk, and give my truck a break!with heavy equipment maybe its expected to run full tilt to get the job done! any owner operators to help me here?
surfer-joe
Senior Member
The bouncing is mostly related to the tires. Cold tires, particularly bias-ply’s, take a set overnight, a flat-spot if you will. It's common to all size tires including radials, though not so bad with the radials. Once the tires get up to operating temperature, they flex more, but they will still launch you to the moon, or the underside of the cab given the chance. Sometimes the bouncing wil only be right at a certain speed, but it will still be related to a tire and it needs looking in to.
The cushioned machines help to take the bounce out thorough a complex hydraulic valving system connected to a load cylinder in the hitch or cylinders connected to the drive axle. It works so that the bounce up is over-ridden hydraulically by the weight of the machine coming down. It sorta balances things out and both systems were a wonderful addition to scrapers when they first came out in the 60's.
There is no easy way to take all the bounce out. The tires have to warm up and the only way to do that is to operate the machine. Sometimes you get a tire or two that have inherent balance problems in them, like a section repair or a big chunk of tread missing, or busted ply’s -- a dangerous condition. Also some tires separate and will cause quite a bounce, if they don't just blow out instead. There is some bounce associated with lose hitch components, and also a bit of bounce that is caused by hydraulic hoses expanding with excessive pressure.
The bounce can be harmful to your health, even cause death from a variety of factors. It's nothing to snort off or fight. Best thing to do is get slowed down or stopped as quickly as possible using the brakes or dropping the bowl very close to the ground. Either way it's rough and hard on the operator.
Overhung scrapers may be a bit worse than six-wheelers, but not by much as my experience has indicated. Bigger tires like 39.5X39's also are a bit better than those on smaller machines with choppy little bumps in the haul road. Bigger bumps and soft spots are bad no matter what you run over them with.
I can remember long strings of scrapers heading out early on cool mornings, some going like hell and some taking it easy. You can figure who was driving like cowboys and who wasn't. There comes a time when operating a scraper just isn't comfortable for older operators, not if they are working a production job. Landscaping or smaller jobs with short hauls is usually different. I dearly love scrapers, but can no longer operate them as I used to. Maybe some of the small tow-behinds, if they are on short hauls.
The cushioned machines help to take the bounce out thorough a complex hydraulic valving system connected to a load cylinder in the hitch or cylinders connected to the drive axle. It works so that the bounce up is over-ridden hydraulically by the weight of the machine coming down. It sorta balances things out and both systems were a wonderful addition to scrapers when they first came out in the 60's.
There is no easy way to take all the bounce out. The tires have to warm up and the only way to do that is to operate the machine. Sometimes you get a tire or two that have inherent balance problems in them, like a section repair or a big chunk of tread missing, or busted ply’s -- a dangerous condition. Also some tires separate and will cause quite a bounce, if they don't just blow out instead. There is some bounce associated with lose hitch components, and also a bit of bounce that is caused by hydraulic hoses expanding with excessive pressure.
The bounce can be harmful to your health, even cause death from a variety of factors. It's nothing to snort off or fight. Best thing to do is get slowed down or stopped as quickly as possible using the brakes or dropping the bowl very close to the ground. Either way it's rough and hard on the operator.
Overhung scrapers may be a bit worse than six-wheelers, but not by much as my experience has indicated. Bigger tires like 39.5X39's also are a bit better than those on smaller machines with choppy little bumps in the haul road. Bigger bumps and soft spots are bad no matter what you run over them with.
I can remember long strings of scrapers heading out early on cool mornings, some going like hell and some taking it easy. You can figure who was driving like cowboys and who wasn't. There comes a time when operating a scraper just isn't comfortable for older operators, not if they are working a production job. Landscaping or smaller jobs with short hauls is usually different. I dearly love scrapers, but can no longer operate them as I used to. Maybe some of the small tow-behinds, if they are on short hauls.
Counter,If the scraper is hopping up and down ,the tire's have flat spots on them.If the scraper is going down a two lane highway at 45 mph hopping up and down, it's coasting on a downhill grade out of gear.Either way ,it's not safe.Everybody knows that scraper tires are egg shaped.