Like most vacuum trucks on the market today, our trucks are powered by way of Power Take-Off. To activate the PTO, you’ll first need to verify the vehicle is in neutral with the parking brake activated. You'll need to flip the PTO switch, which is found on the inside of your cab, or on the outside of your truck. The location of this switch can vary from truck to truck so you will need to familiarize yourself with that during your pre-trip.
Once you’re PTO is activated, it will power up the pump. This exchange of power is established through a rubber sleeve that sits between the PTO shaft and the pump shaft. These rubber sleeves can look different depending on the truck you're driving. Knowing this, it's important to inspect them for damage or wear and tear. If excessive damage were to arise on either side of this rubber sleeve, it's designed to break free and prevent damage to the pump and/or the PTO.
The vacuum pump is an oil-sealed displacement pump, which utilizes centrifugal force to generate suction. Like most standard vacuum cleaners, it was not designed to get wet; therefore, several layers of protection are required to keep waste and chemicals from getting into the pump.
Your pump’s first line of protection begins with the primary shut off trap. This trap is often welded into the top of your tank at the "manhole," and uses a float ball to shut off the air suction as the tank begins to reach the top. This trap is extremely important as it prevents waste water from entering into the pump and potentially onto the ground.
As you can imagine, it’s important to have several layers of protection should the primary trap ever fail. This brings us to our secondary trap, also known as a scrubber. You can easily identify the secondary trap by following the hose from the top of the waste tank. This hose can be found at either the top of the tank coming from the "manhole," or beneath the waste tank where it will run through the truck frame. The trick is to follow the hose from the tank, as it will always lead you to the secondary trap.
The secondary trap, also known as the secondary scrubber, is your second line of defense should the primary trap ever fail. It also works to catch carryover that can often happen during transport. Similar to the primary trap, the secondary trap utilizes a float ball to shut off overflow into the pump. It also helps separate liquid from the air stream, keeping your pump free from unwanted fluids.
We’ll now follow the hose from the secondary trap as it makes its way to the vacuum/pressure valve, located on top of the pump. This is where you can select vacuum or pressure by moving the lever from left to right and back right to left. Please note, this lever can be reversed on some trucks. Always reference the yellow sticker, which is located near the valve to accurately identify which position is which.
We’ll now continue our journey through the pump and into the oil separator. The oil separator is there to catch any used oil that may have spilled over from the vacuum pump. It’s also used to muffle any loud exhaust sounds that can often resonate from the pump.
The last component of the pump system is the exhaust vent. This will always be located right off the oil separator. The exhaust vent is there to release excessive pressure from inside the tank during suction; therefore, it’s important that you always keep this vent unobstructed.
Each vacuum truck also includes a vacuum and pressure relief valve. These discretely mounted valves are found throughout vacuum system on your truck. They were designed to automatically release air as it builds up inside the waste tank. These will work to prevent an unwanted tank collapse or tank explosion, should pressure ever exceed the recommended limit. To monitor your tank’s pressure, you can utilize the vacuum pressure gauge, which is often found near the pump itself. The ideal operating range will always be set by our mechanics prior to use.
To ensure your vacuum pump stays lubricated, your truck is equipped with an oil reservoir. The oil reservoir is typically located above the pump and will have a single gravity fed line which feeds directly into the pump. As part of your pre-trip, it’s important that you visually confirm you have enough oil inside this reservoir to last the day. If not, it's important that you fill it back up with more pump oil which is located in the garage.
As you can see, there are a lot of moving components inside your truck that give you the required suction you need to last throughout the day. Each of these components plays an important role in keeping you and others around you safe. Should you have any additional questions on the operation or the safety features of your truck, please reach out to a member of our driver services team for more information.