Striking a balance

Operators consider many factors when purchasing a crushing and screening machine, but ease of maintenance should be a top consideration, says Tyke van Zandt, operations manager for Lodi, California-based FTG Construction Materials.

Frank C. Alegre, owner of Frank C. Alegre Trucking Inc., founded FTG Construction Materials. He believed there must be a use for “all the broken concrete that was getting left on the side of roads, in piles and fields,” van Zandt says.

“[Alegre] eventually proved he could make what we call in California ‘spec road base,’” he says. “He’s recognized as the first person in the industry to try it and pull it off.”

Van Zandt says he manages aggregate recycling yards in Antioch, Stockton and Lodi, California, that process asphalt and concrete for use as road base.

A large part of the operation at the three properties involves Astec crusher/screeners, which sort and size material for road base, he says. FTG Construction Materials runs two Astec FT4250 crushers and an FT2650 jaw crusher at its facilities.

Access to the blow bar chamber

When selecting a crusher, van Zandt says ease of maintenance is a key consideration that can affect machine efficiency and life span. The process of installing new blow bars is particularly important. Blow bars typically are attached to a rotor. The spinning blow bars smash the aggregate against the walls of the chamber, reducing material size in the process.

“Those have to be changed out every 10 days if you’re running eight to 10 hours a day without any issues,” van Zandt says. “You’ll want something that is going to be less difficult to replace.”

Manufacturers have headed in different directions when it comes to design, he adds. For instance, the height of the blow bar chamber and the space within it differ.

He says Astec Industries offers a design where the blow bars are 4-and-a-half feet off the ground. “When you open the crusher box to work on the internals, three full-size, 200-plus pound men can get in there and work.”

He says some competing models have smaller chambers that maintenance workers must access from the top of the machine, which is not ideal.

“Naturally, the tools are in the service truck down on the ground,” van Zandt says. “You start going up and down ladders a lot, and if you’re trying to carry tools or something of that nature, your chances of something going wrong go up. … You’re going to slip or you’re going to fall or you’re going to drop something. And, if you do drop something, now you have to climb all the way back down, pick it back up [and] go all the way back up again.”

One reason van Zandt says operators could consider a machine with a smaller chamber is the ease of transportation. While he says FTG does not move its equipment among its three yards, firms that need to move crushing machines frequently could benefit from having a smaller blow bar chamber.

“Obviously, they have to be put on a truck in order to be hauled any length of distance,” he explains. “If you can make it smaller, you can use a smaller trailer or a smaller truck, which is going to cost less. … In the state of California, you can legally haul a Powerscreen on a seven-axle trailer. For a KPI or an Astec crusher, you’re going to need a minimum of a nine-axle trailer, and a lot of guys run a 13-axle trailer.”

Remote control

Depending on the material the machine is processing, the feed rate must be adjusted.

“Some things crush very easily; some other things aren’t quite so easy,” he says. “It’s kind of a balancing act.”

Van Zandt says this is where having a remote control can be a significant benefit to an operation.

Astec remote controls enable operators to speed up or slow down the feeder during operation.

“With all the other manufacturers, you actually have to get off the machine you’re on or holler at someone on a radio to physically walk over to the unit, open the door to the control panel and either speed up the feeder or slow it down.”

Using the remote, Astec operators also can move the machine as it’s crushing, which van Zandt says can be beneficial in a highway setting.

Powercreens offer remote control, as well, but he says it does not enable the machine to move while operating.

In some respects, safety and efficiency go hand in hand. One example is providing ease of access to machine parts and minimizing the need for ladders, he says.

However, van Zandt says he’s less of a fan of electronic lockout sensors. For example, on a Powerscreen model he tried, he says the door to the crusher box was tied to an electronic sensor that prevents the machine from being operated while the door is open.

“Well, if that sensor goes bad like it did when we were demoing one, you’re dead in the water,” he says.

He explains that the lockout sensor malfunctioned, indicating that the door was open when it was not, resulting in downtime.

Safety features such as this one are important, but workers and others near the machines need to take responsibility for their own welfare, as well, he says. Safety should be balanced with efficiency.

To keep maintenance workers safe, van Zandt says he limits the number of employees around machines and requires operators to account for all laborers before beginning.

Dust suppression

Operators have a couple of options available to suppress dust on job sites: spray systems and conveyor covers. Van Zandt says he often prefers using sprayer systems.

On the Astec machines FTG Construction Material uses, sprayer systems are positioned at the points where aggregate falls on the conveyors and screens, dampening material as it falls and preventing the impact from creating dust. Spray nozzles can be adjusted depending on the situation.

On some other machines, cover systems are installed over the conveyor to contain dust, van Zandt says.

“If everything is working ideally, it’s very effective,” he says of conveyor covers. “The one thing you will learn with crushing systems is that there is very seldom an ideal moment. It’s just the nature of the beast. There’s always something that’s not quite correct.”   

If the crusher becomes jammed—which van Zandt says is not unusual—covers create extra work for operators.

“Now, you have material that has not been crushed,” he explains. “It has gone through the crusher box onto the conveyor. So, instead of having [softball-size material] on your conveyor belt, now you have basketballs on it.”

Some conveyor belt covers do not permit larger pieces of aggregate to pass through, he adds.

“So, now you have to unbolt all those covers, move them off to the side, correct the issue and get everything back up and running again,” he says. “I can tell you from experience it’s going to take you an hour to an hour and a half just to get the darn things off.”

Taking off the conveyor covers also requires using ladders, “standing on a conveyor that has no handrails and no side rails” and handing the covers to an employee on the ground so they don’t get bent. Van Zandt says conveyors often are 6 feet to 10 feet above the ground.

Spray systems can have a tendency to form mud if too much water is used, van Zandt says.

“We use tips,” he says. “It’s a fan spray—a little bit more than a mist but not a lot. You can stand under one for probably 30 seconds or 45 seconds and not really get wet.”

For van Zandt, the priorities are safety and ease of maintenance, including easy access to areas of the crusher that frequently require work.

“We don’t want to have to stop crushing for any particular reason,” he says. “Once you’re crushing, you want to stay crushing until the end of the day.”

The author is the managing editor of Construction & Demolition Recycling magazine and can be reached at bgaetjens@gie.net.