Troubleshoot placing your apparatus into pump gear
Thursday, July 13, 2017
Several times during my career I had been called out to evaluate a driver engineer/chauffeur having an issue placing a pumper truck into pump gear. Many times, it was due to operator error.
The scene of a fire is a high-energy, adrenaline-packed environment. It is common for mistakes to happen when caught up in the excitement. Learning to take control of your emotions and take a step back to rethink what is happening is a good way to solve issues when a situation goes awry.
Remember, it is important to get water flowing at a fire. It is the heart and soul of getting it under control. Once water is put on the fire, things immediately begin to get better — it's not rocket science.
There are several steps a driver can take to troubleshoot placing your apparatus into pump gear when it doesn't go in the first time. Understanding the theory, a driver can "visualize" what might be going on.
Most apparatus pump in "drive." Some of the procedures in this article won't apply for those pumping in" neutral."
One basic concept is that there can be no tension on the drive shaft/driveline. This is the part that spins when any vehicle is in motion. It is what directs the forward (or backward) motion of a vehicle. It is the part that goes from the rear of the engine via the transmission to the differential, which diverts the motion/energy to the rear wheels on a rear wheel drive vehicle.
There are many variations of this because of front-wheel drive, four-wheel drive and all-wheel drive. For this discussion, we will talk about rear-wheel drive.
Pumper trucks have what they call a split shaft, meaning that the driveline/shaft is split into two parts. This is because the front part goes from the transmission to a transfer case to drive or turn the pump, then from the transfer case to the rear differential.
When an apparatus is in "road" mode or gear, the drive shaft spins through the transfer case to the rear drive shaft. When in "pump" mode or gear, the rear drive shaft is disengaged via a shift collar.
Subsequently, the front drive shaft is now turning the mechanism in the transfer case to turn the pump impeller, via a chain-driven mechanism, and the rear drive shaft is disengaged and not spinning. If it were, the rear drive shaft would cause the rear wheels to move the vehicle forward — not a good thing if you need to pump. You would be running the down the street to try to get into the cab to stop it!
Therefore, it is good to get into the habit of placing the vehicle into neutral first, then applying the parking brake. What you do not want to do is apply the parking brake while the truck is still in drive and then switch to neutral. When the latter occurs, what you have done is locked the driveshaft under tension rather than having it in a free spin mode.
That is why some of us may get that characteristic "knock" when placing it into pump gear or shifting out of neutral to drive. This is the equivalent of parking your car in a parking space, having the tires against the concrete parking stop or curb, then placing it in park without letting the vehicle back off.
The same concept applies when parking on a hill. Put your foot on the brake, shift to neutral, then apply the emergency brake, then shift to park. I have always made it a habit in my personal vehicle to use the above-mentioned "hill" procedure regardless of my terrain or street conditions.
Most pump/shift systems work on a pneumatic system. Therefore, the pump/shift operations may not work if the truck has low air pressure.
It is always a good safety practice to have wheel chocks in place once the truck is spotted and ready to pump. Be sure to leave a little space between the tire and the chock so that the chocks don't "dig in" to the roadway from vibration.
Depending on the type of pump shift operations system you have on your trucks, the following basic troubleshooting sequence is what we used at my former department (this may not apply if your truck pumps in neutral).
If the truck does not go into pump gear and you do not get the OK to pump or "pump engaged" light to illuminate by performing normal seat operations, then:
- Reverse the procedure and repeat the seat operations (remember to shift the truck back into neutral prior to turning off the pump/shift actuation knob). Then, try to place in pump gear again. If this still does not work, then;
- Take the truck out of pump gear and cycle the transmission from neutral to drive to neutral to reverse then neutral again. Then try to place in pump gear. Then try to place in pump gear again. If this still does not work, then;
- Take the truck out of pump gear and physically move the truck one to two feet, either forward or reverse, or both. Then try to place in pump gear again. If this still does not work, then;
- Take the truck out of pump gear, and move to the manual pump shift override procedure as suggested by the manufacturer's operator's manual for your truck. This is usually located at the pump panel. Then try to place in pump gear again. If this still does not work, then;
- A two-man operation may need to occur due to manipulation of the drive shaft occurring simultaneously while the manual pump shift override is manipulated.
A great resource is the following two-part video made by my former department and previous driver engineer instructor:
Take the time to become familiar with this procedure. Especially practice the manual pump shift lever operation to assure you get a feel of the mechanisms to "knuckle" in and mesh. Be safe!
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