I have encountered this problem that can stop you from pumping a few times with customers. They get their pump fully restored and are ready to pump concrete. The concrete arrives at the job site and they start pumping. Everything is working under normal conditions and then all of a sudden, they are stopped right on their tracks.
Stoppage in the Middle of a Pour is a Big Problem
One specific case happened a couple of weeks ago with a Florida customer. They called me to explain that their newly restored pump stopped pumping, and they could not figure out why. They checked the diesel. Then they checked the engine. They checked everything. Still no solution, and unpoured concrete is starting to settle inside their brand new wear parts and on their brand new paint job.
People complain that the engine is not responding. Some people might even take it as far as spraying quick-starting fluid on the air filter, potentially damaging the pistons in the process.
We offer a tip to help get you back to pumping quickly and prevent damaging your newly-restored concrete pump. If you turn the key on a trailer pump and don’t hear a clicking sound, it’s an electrical problem that is normally related to an E-stop malfunctioning. A clicking sound is the fuel solenoid opening up and allowing the passage of diesel through the main lift pump. So if there is no “clicking”, then there is no fuel.
Check Everything Electrical on the Pump
After the customer called us, we had the operator test the connections of each electrical part in the machine, starting with the water box safety devices, passenger side controls, and operator control safety device. These are the most delicate and complicated connections.
After checking every single one, all the parts seemed functional (they are normally brand new on refurbished pumps from us). But the concrete trailer pump still did not respond. While figuring out the next plan of attack, I heard an engine start in the background and they said, “Everything is fine.” They hung up the phone and we left it at that.
About 30 minutes later…
We get another call with the same issue. We were as frustrated as our customer that we couldn’t figure out what was happening with this pump. Why was it stopping like this? My mechanic then asked the customer to send him a cell phone picture of the operator control box from both the outside and inside. When we got the picture, we saw that all the connections were properly hooked up, there were no loose cables, no exposed wires that might indicate a bad ground, NOTHING.
Consider Safety Devices That May Have Stopped Pumping
But then we noticed something peculiar on the outside picture. The hopper was full over the top with concrete and the load was lifting the hopper grate.
We checked our records on this customer’s unit and noticed that this model has what’s called a “hopper grate safety switch”. This stops the whole system from moving when the grate is lifted, to protect the operator from getting hurt. In the event that the operator wants to get his/her hands inside the hopper while the machine is engaged in switchover motion, the switchover function will cease to work as soon as the hopper grate is raised.
Check out this video of what happens when a hopper grate opens… pumping stops.
Problem solved. I called the customer to explain what was happening, and we were able to resolve this easy but distracting issue.
So, if you have a hopper grate switch on your pump, make sure the device is not frozen or that anything is lifting the grate off the top of the hopper. Otherwise, you could spend hours troubleshooting while concrete sets in the pump.
Also, PLEASE resist the desire to bypass any safety devices on any pump. They are there for the safety of you and your operator.
