Hydraulic Winch System Maintenance & Repair
Troubleshooting Hydraulic Winches for the Speed Screed Cruiser and Heavy Duty Concrete Finishers
In this session, we’ll do an overview and trouble-shooting of the hydraulic winch system for both the speed screed cruiser and the heavy duty concrete finishers. First, we’re going to do an overview of the parts that make up the hydraulic winch system. Then we’ll go over how the system works. Then we’ll wrap up with some common trouble shooting tips.
Speed Screed: Top-Quality Parts Assure Peak-Performing Winch System
So first, the parts that make up the hydraulic winch system are the tank, flow control valve (or integrated hydraulic control), the hydraulic motor, the winch spool with cable, the quick disconnect knob, the hydraulic pump which is mounted on the end of the screed, and the pump drive coupling which connects the main shaft to the hydraulic pump.
Now that we’ve reviewed the parts that make up the system, we can go over how the system works. We have a direct drive system which means the main shaft turns the hydraulic pump directly not using a second secondary belt or pulley system. So the main shaft turns the hydraulic coupler which in turn turns the hydraulic pump. When the main shaft is turning, you will have oil pumping throughout the complete system. When the flow control knob is fully disengaged, or on its slowest or off setting, the oil will be pumping through the complete plumbing right back into the tank without turning the hydraulic winch screed. As we tighten the turn-in (the flow control valve), oil starts to get forced through the system back through the hydraulic motor which turns the winch spool and pulls the screed forward.
Speed Screed: Trouble-Shooting When Winch Spool Stops Turning
Now that we’ve reviewed all the parts and how the system works, we’re going to do a few trouble-shooting techniques that might come up from time to time.
One issue that comes up once in a while is that contractors will say that their hydraulic winch spool has stopped turning. Won’t turn at all. We want to run a couple checks. One check is to make sure our belt tension is correct on the engine and that the pulley isn’t spinning on the belt. Another thing we want to check is that when we put the screed together, we didn’t accidentally miss some set screws on the main drive shaft which means part of the shaft is turning and part of the shaft isn’t turning. We also want to check with the screed running full throttle. We want to make sure that our flow control valve is turned all the way in for max speed and that our quick disconnect knob is fully engaged into the winch spool. Without it fully engaged in the winch spool, the winch spool won’t turn. Just the hydraulic shaft will spin inside of the winch spool, so it’s very important to check that the quick disconnect knob is fully engaged in the winch spool which doesn’t allow the spool to turn.
So if the screed shaft is spinning, we want to check and make sure the main shaft is turning the love joy coupler or the pump drive coupler. If it’s not turning, either one of the set screws has come loose or fallen out or got sheared off in operation or perhaps the rubber spider gear inside has disintegrated over time. So after we’ve checked the hydraulic drive coupling and the main shaft-- make sure they’re both spinning – we want to start to focus on the hydraulic motor and winch spool assembly.
Speed Screed: Check if the Hydraulic Pump is Working
We’ve established that the shaft turns and the pump drive coupling spins. What we want to do now is shut the screed down. We want to pull out the disconnect knob. And remove the bolt that holds it to the unit. Take off the cover. Once we get the cover removed, we want to unwind all the cable that is on the spool itself. Once we get all the cable off, we’ll see that there’s a set screw on the spool that holds it to the main shaft coming off the hydraulic motor. Remove the set screw. Pull off the disconnect. Pull the spool off. And we should see the hydraulic shaft which looks like this (5:01) inside connected to the hydraulic motor. Now on this shaft are a couple set screws. If those set screws have been sheared off or came loose over time, maybe the hydraulic motor shaft is just spinning inside of this. If they are fully engaged or still in there, and you can’t turn this by hand, we’ve just established that there’s nothing wrong with the hydraulic motor or the shaft or any of the spool components. So now we can focus back on the hydraulic pump. We know that the shaft turns, the coupler turns and that the hydraulic motor and spool system is all engaging properly. So we’re going to say that the hydraulic pump has ceased to work. It’s no longer pumping oil to the system and needs to be replaced.
Speed Screed: Trouble-Shooting When Screed Is Lurching
Another issue which comes up from time to time is the screed turns a little bit -- it stops, it lurches, it jerks -- when it’s pulling in the cable. So when that happens, you just want to make sure the cable hasn’t become tangled or wrapped around some other obstacle which might prevent it from wrapping up. If that’s not the case and everything is wrapped properly, we want to check the flow control valve and make sure it’s operating properly. If you’re not getting proper control over the winch spool, the hydraulic control unit has probably failed. Due to contamination of oil or just over time the pressure regulator inside the block might have broken down. So at that point we want to make sure to replace the unit, put on a new hydraulic flow control valve and put you back in business.
So in review, one of three things generally can go wrong. And that might be the pump drive coupler being loose. The hydraulic pump --which either going to be an on or off system (either it’s going to work and spin the motor or it’s not). It doesn’t work halfway. It’s not like if it’s jerking, it’s a hydraulic pump problem. If it’s on or off and doesn’t work at all, the hydraulic pump is likely a suspect. If it jerks or doesn’t operate smoothly, your hydraulic flow control valve is most likely where you want to start and replace that.