Just One Hand

The Omnibus controller on Vac-Con combination and hydroexcavator trucks lets operators regulate all water and vacuum system functions from one joystick

Sewer jet-vacuum truck oper-ators often have a number of control points to attend to as they reel water jet hoses in and out, raise and lower vacuum booms, adjust engine speeds, and turn emergency lights on and off, among other tasks.

Vac-Con Inc., manufacturer of Vac-Con combination vehicles, has introduced the Omnibus control system, which consolidates all the separate switches, levers, instruments and other water and vacuum system controls into a single joystick. The control handle is mounted to the top of the truck’s hose reel panel. Beneath it, a menu-driven digital monitor displays a full range of operational parameters and replaces the instrument panel found on conventional trucks.

A simple wiring system ties the joystick controller and the digital monitor into a “brain box” mini-bus behind the truck cab. All circuits are accessible at that single point, and additional sensors can be added to the box for other operational functions as needed, or to suit a customer’s specific application needs. The company says the Omnibus control system is attractively priced compared to conventional control systems. It is available on Vac-Con combination and hydroexcavation trucks.

Mike Shelton, Vac-Con sales technician, demonstrated the control with help from the Wausau (Wis.) Wastewater Treatment Utility on Friday, July 17, just a few weeks after the product was introduced. Assisting was Wausau sewer maintainer Mark Sowinski.

Walk-around

The joystick controller sits atop the hose reel case at the operator control station at the front of the truck. Grip-shaped, the stick features push buttons on its top or thumb area.

These buttons control the position (articulation) of the hose reel, which swings 180 degrees for accurate positioning. They also control starting and stopping the auxiliary engine that drives the water system, raising and lowering the vacuum hose, and throttling the water pressure up and down. A small red pilot light above the buttons indicates whether the auxiliary engine is running.

On the back, or finger side of the stick, another switch toggles in two directions: Pushing it up controls the speed of the hose reel revolutions. Pushing it down activates the boom directional controls.

Below the stick, on the side panel of the hose reel case, a clear digital monitor panel about 4 inches wide by 6 inches high displays a menu of functions. A function selector switch and three specific function activation buttons are directly below the panel. Below them, simple directions and illustrations explain the operation of the joystick.

On the front of the hose reel panel, large lever handles enable the operator to start the water flow to the hose reel and control the water pressure. A third valve increases or decreases the water flow to the hose. Shelton explained that nozzle and line sizes may require different water volumes, and it is wasteful to pump more water than needed.

Operation

Shelton first filled the brand new combination truck’s tank with water at a hydrant at the Wausau treatment plant. He then positioned the truck, equipped with the Omnibus control, next to a manhole at Emter and Adrian Streets on Wausau’s west side.

After a brief rain shower, Sowinski and Shelton donned safety gear and went to work. Sowinski popped the manhole cover, exposing access to a 7-inch sewer line, and helped Shelton attach the jet nozzle to the end of the hose and position the hose over the manhole.

Shelton positioned himself at the operator control station. Working off the controls on the hose reel case, he turned on the emergency arrow flashers to warn motorists to pass by carefully on the left or right side of the truck. He explained that the controls include a strobe light switch for night or low-light operation.

Next, Shelton demonstrated how the joystick controller is used to articulate the water hose reel, swinging the reel through a 180-degree arc across the front of the truck. This capability allows different positioning of the hose in case of tight conditions. Since he had clear access to the manhole, however, he swung the hose reel back to its normal position and activated the hose reel, unrolling the water hose into the manhole and up the sewer line.

Sheldon’s right hand grasped the joystick, and his index finger depressed the toggle switch in the upward direction, controlling the revolutions of the hose reel as the hose continued into the line. With his left hand, he helped guide the hose through the bail into the manhole. To turn on the water flow, he dropped his hand down to the water flow and pressure controls below the joystick on the face of the hose reel case. The pressure and flow readings appeared on the digital monitor on the end of the case. He did not have to move during the entire operation.

After several minutes, Shelton turned off the water and moved the joystick to begin extracting the hose from the line. When it was recoiled, he switched the controls to the vacuum boom. Again using the joystick and toggling with his index finger, he positioned the boom over the manhole and lowered it into the space.

At this point, Shelton allowed me to operate the controls. He showed me how to depress the toggle and move the joystick forward and back to raise and lower the boom, and from side to side to move the boom left or right.

At first, I was too aggressive with the stick and banged the aluminum pipe at the end of the vacuum boom against the side of the manhole. As I repeated the process, I began to get the feel of it, and realized that I needed only a slight movement of my hand to move the boom.

The unit being demonstrated was equipped with an auxiliary engine-driven hydraulic operating system. This means all functional hydraulics — hose reel, boom, dump, and rear door — operate only when the auxiliary engine is running. The auxiliary engine also drives the water pump to create flow and pressure.

The chassis engine drives the hydrostatic system, which operates the vacuum system. In other words, if using only the waterjet system, it is possible to operate with the chassis engine shut down. If the operator wants to use the vacuum system, then the chassis engine and auxiliary engine must be running.

“Our most popular configuration uses the chassis engine to drive the vacuum and functional hydraulic systems, but this unit was equipped with the optional auxiliary-engine-driven hydraulics,” notes Vac-Con marketing manager Tom Jody. “So, if we know that most of the work being done will be waterjet work, then we recommend this optional system because it is much quieter and more fuel efficient to operate with only the auxiliary engine running.”

After the hose reel and vacuum boom were stored, Shelton walked around to the back of the cab to show where the “brain box” was situated. He unfastened and opened the covering to expose the circuitry and explained how the Omnibus system reduced the amount of wiring found in conventional control systems, easing troubleshooting and repairs.

To illustrate, he returned to the front of the truck and, dialing up the menu on the digital monitor, showed the control grid. “If there were to be an electrical problem, it would show up on the grid and the operator could immediately identify where and what the problem was,” he said.

Observer comments

The rig and Shelton’s demonstration were impressive, and Sowinski noted that the Omnibus system provided all the necessary controls at the operator’s fingertips. Shelton did not have to leave his station at the front of the truck at any time during the demonstration, except for the walk back to the “brain box” mini-bus.

It was apparent that if moving around the rig to activate different controls is an issue, the Omnibus control is a useful solution. The joystick is rugged and solid, and appears able to withstand substantial pushing and pulling. It was also clear that it might take operators a little time to become accustomed to its sensitivity.

Without practice, it was easy at first to push the stick too far or too fast. The picture directions printed on the panel were helpful in understanding how the joystick worked and what functions it controlled. While the digital monitor brought all the readings to a central location, the characters on the screen seemed small and difficult to read. Any glare coming off the clear screen covering made that issue more pronounced.

Manufacturer comments

Jody points out that the sensitivity of the joystick control is adjustable. “We think that as we put more machines in the field, we and the operators will gain a better feel for this,” he says. He notes that adjusting the contrast and backlighting controls improves the visibility of information on the monitor. The operator makes these adjustments on site based on conditions (day or night, sun or clouds).

“We have already effected one permanent font change, and again will monitor feedback from our sales technicians and customers to improve function,” Jody says.

On the issue of fuel consumption, Jody notes that when the control hydraulics are operated with the auxiliary engine, that engine may use less fuel than the chassis engine, depending on conditions. He adds that Vac-Con has a larger hydrostatic pump that allows the chassis engine to operate at a much lower rpm, while still achieving full vacuum power. “The resulting fuel savings is as high as 40 percent at full vacuum with a reduction of 5 decibels in noise at the operator’s station,” he says.

Jody notes that the new system is quite powerful, so full vacuum may not be required in many cases. “This allows us to operate the engine at even lower speeds to further reduce fuel consumption and noise,” he says. “We’ve actually documented the fuel consumption rates.”



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