paver screed issues

[Manny530]

ive owned my Gilcrest ProPaver for about 4 years now and the last few jobs i have used it on i have noticed that the screed like to move around on me varying the thickness of the mat. its frustrating me at the moment because it is causing me to have to do alot more work. i was wondering if anyone has ever had any simular issues with any of their pavers and what may be a fix?

 

[huckleberry]

you should check all your pivot points for slop. a little slop in each point adds up. also check your depth crank's, if the threads are worn they will let the screed move. null the screws out and lift the screed and step on the cat walk . you will be able to see movement at screws & pivot point on screed. I haven't worked on gilcrest pavers very much, if you have play in your ext's than they will move and change also.

 

[Manny530]

deffinatly going to look into all of those things. when i lift the screed the left side starts to lift before the right and when i sit the screed down it one side hits the ground before the other so was maybe thinking because they didnt lift and lay at the same time that may be an issue. also when i sit the screed down fully i notice the rest of the machine rocks forward like as if the hydraulic cylinders on the screed are pushing the screed to far down causing the rest of the machine to pivot. i will post of some video to show you what i mean kinda hard to explain im not to sure if this is normal or not.

 

[huckleberry]

the screed will lift up and sit down like you said. it's just the nature on all screeds. when you sit the screed down it takes the weight off the back of the machine. you can see it more on smaller pavers because the tracks are shorter. all pavers do that. when you lift or lowering the screed the fluid goes through a valve to activate both cyl's.

 

[Manny530]

Yeah I have a pucket brothers gravity feed paver and that screed like to jump around on me but I always assumed the cause was the screed being so light. I usually like to have someone running the other side of the paver but the last couple times I've had to run it myself and seems like that's when it likes to move on me. Thanks for your feed back.

 

[drummer]

Your screed lift cylinders may need to be rebuilt (new packings/seals) to stop the uneven lift. When you set your screed down on the mat or boards that you start from, the screed is in "float", the lift cylinders are not putting any hydraulic pressure down or up. Check for wear in your bushings in the screed extensions if so equipped. Check your screed arm tow points for any movement. These are all wear points (replaceable) and quickly change the finish in your mat. Pull a string line under your screed from side to side or use a straight edge to check screed alignment. Adjust to correct. When paving, try to keep the asphalt head at a constant feed and amount in front of the screed. The screed will dive when it is too little, and fights to rise when overfed or running over a spilled pile from the hopper or a truck.

 

[Manny530]

Your screed lift cylinders may need to be rebuilt (new packings/seals) to stop the uneven lift. When you set your screed down on the mat or boards that you start from, the screed is in "float", the lift cylinders are not putting any hydraulic pressure down or up. Check for wear in your bushings in the screed extensions if so equipped. Check your screed arm tow points for any movement. These are all wear points (replaceable) and quickly change the finish in your mat. Pull a string line under your screed from side to side or use a straight edge to check screed alignment. Adjust to correct. When paving, try to keep the asphalt head at a constant feed and amount in front of the screed. The screed will dive when it is too little, and fights to rise when overfed or running over a spilled pile from the hopper or a truck.

Thanks for the reply I think I'm going to have the lift cylinders rebuilt just so I can rule that out. I was under the assumption that maybe the reason it wasn't lifting together had to do with the valve but then again I don't know much about hydraulics. I checked the lifting point and there is some play so going to tKe that apart and see if I can put a new bushing in there. Any other ideas will be welcomed I'll keep you posted if any of these changes work

 

[huckleberry]

if you leave the screed up with engine running and if the screed doesn't settle down then I wouldn't believe that the cyl's are bad. what condition is your screed plate in ? if its worn & warped than you could be fighting the issues. set your screed down on flat surface & null depth screws & check the screw length (exposed threads) on both screws. these should be close to one another. if not your plate could be worn & twisting when paveing. Like drummer said use a string line or a straight edge to check your plate. when using a string line I will use a 1/8 shim on each end of the plate & use another shim to check at different spots. if it checks good, then check from corner to corner & if you can see a lot of crown than your plate is warped. when I check from corner to corner I use a straight edge. that way you can see if it's crowned or has a invert in it. when you lift your screed, look at the depth screw bearings & if they are worn or the screw moves in it. I hope that I'm not confusing you. there is quite a few things to check.