No examination of toolcarriers is complete without a comparison to wheel loaders. The two machines are closely related, with their main difference being the types of linkages they employ to manipulate attachments. Wheel loaders use a Z-bar linkage configuration, which is highly specialized for digging applications. Toolcarriers are equipped with parallel-lift linkage, which sacrifices some breakout force capability in exchange for increased attachment use and greater up-front articulation. Just as important is the toolcarrier’s ability to maintain a load parallel to the ground all the way through the linkage’s range of motion.
Deciding between a toolcarrier and a wheel loader for your work is an application-driven decision. Toolcarriers in the 130- to <200-horsepower range are most often used in utility and bridge work plus heavy highway applications. Sewer and pipeline work on roadways is a common application. Since both wheel loaders and toolcarriers can excel in this type of work, Andrew Bonde, product marketing manager, John Deere, says you'll need to examine application ratios.
"If you're going to both dig and carry pipes with the machine, you need to figure out what percentage of the time the machine is going to be doing that kind of work," Bonde says. "If you spend more than 50 percent of your time digging or loading then you're better off with a Z-bar machine. But if it turns out you're only going to be digging 20 percent of the time, and 80 percent of the time you'll be using forks, grapples or some other kind of attachment, then you need a toolcarrier. Remember that your ultimate goal when deciding between the two machines is to guarantee as much use as possible."
Constant breakout force throughout lift cycle
Z-bar loaders are configured for digging applications. As such, their linkage geometry is optimized to provide maximum breakout force when the attachment is poised to cut into a pile. Toolcarriers, on the other hand, have near constant breakout force throughout the arc of their linkage geometry (the linkage’s range of motion). “A toolcarrier’s potential breakout force will decrease a little as the bucket linkage raises or lowers, but not as drastically as the decrease is with a Z-bar machine,” notes David Morice, product manager, JCB.
In many cases, Morice says, toolcarriers will retain 85 to 90 percent of their potential breakout force at ground level as you raise the bucket. “This gives the toolcarrier the inherent strength to precisely handle loads at different levels,” he notes.
If, for example, you’re feeding material into a hopper at a steady rate the toolcarrier’s near constant level of force struts its stuff, Morice says. “The parallel life linkage gives you the ability to feather the load combined with enough breakout force to hold the angle of the bucket as it dumps the material. A Z-bar machine doesn’t have the reserve energy to meter a loaded bucket and will just dump it all the way.”
Bear in mind that toolcarriers have some disadvantages you should consider, according to John Frame, marketing manager, New Holland. “In addition to reduced breakout forces, toolcarriers often have slower hydraulic cycle times than a comparably sized wheel loader with a Z-bar linkage,” he says. “Because of this, the tool carrier operator may have to spend more time prying out rocks or loading the bucket in tough digging conditions such as frozen soil or clay. Furthermore, the operator may need to approach the truck or hopper more slowly to give the loader arms time to cycle to the required height when engaged in load-and-carry work.”
Another advantage toolcarriers offer is their third spool hydraulics, although Gary Bell, vice president and general manager, Kawasaki Construction Machinery, says there are some misconceptions about these systems. “Some contractors believe that if they have a toolcarrier they need third spool hydraulics to handle the coupler and attachments,” he says. “That’s not usually the case. Most couplers have locking pins handled with a diverter valve off a two-spool system. Unless you’re running an attachment that has a third function such as running a top clamp or side dump function, there is no reason to have a third spool. If you’re just using it to actuate a coupler, it’s overkill.”
Creativity counts when measuring toolcarrier productivity
Defining toolcarrier productivity can be a simple or complex task, depending on the application at hand. Because a toolcarrier can dig and load-and-carry effectively, productivity can be measured simply as the amount of material moved in a given length of time. “The measure could be cubic yards or tons of fill gravel moved, feet of water pipe laid or number of precast forms set,” Frame says. “If you have a good understanding of the hourly owning and operating cost of the toolcarrier, then it’s pretty easy to measure productivity in terms of tons or cubic yards per dollar of owning and operating cost.”
Things become more complicated when the toolcarrier is primarily engaged in attachment applications. Often, in attachment work – running a broom or using forks, for example – productivity is gained simply by completing the task at hand. Still, if tracking tool usage and machine effectiveness is important to you, there are methods available to help you get a handle on the numbers.
“It’s fairly easy to track the number of hours that a specific attachment is working and record the kind and amount of work that has been done with them,” says Mark Barden, wheel loader marketing manager, Caterpillar. “You can even put a notepad in the cab and have your operators track this information.”
Barden says the types of information recorded can vary widely and be easily tailored to meet your needs. “Time is probably the easiest to measure,” he notes. “You can also track amount of material moved (pipes, for example), the distance traveled by the toolcarrier and the amount of fuel consumed doing a particular job. Ultimately this information can be used to yield the tons or cubic yards of material moved per hour and amount of material moved per gallon of fuel.”
Match buckets and material density for greatest productivity when digging
Despite a toolcarrier’s natural emphasis on attachments, these machines still spend most of their time working with buckets (forks are the second most commonly used attachment). Although toolcarriers can work effectively with buckets, compromises still have to be considered when running the machine. “Right off, you’ll notice that a toolcarrier gives you the advantages of extended reach and higher dump heights,” observes Dave Wolf, product manager, Case. “But the same geometry that gives you that edge also reduces bucket capacities and operating loads.”
This reduced payload capacity can be further exacerbated if your toolcarrier is equipped with a quick coupler. “You can use the same size buckets (generally 3 cubic yards in these classes) on a toolcarrier that you would on a comparably sized wheel loader,” Bonde says. “But you do sacrifice a little bit of stability since the coupler forces your load further in front. This leads to a little bit of porpoising when moving the machine since your fore and aft stability isn’t as good as it would be with a Z-bar machine. Conversely, a toolcarrier without a coupler allows it to carry a load closer in to the machine’s center of gravity.”
It’s also worth noting that a machine’s ground engaging tools, the type and density of the material being excavated and handled, as well as underfoot conditions greatly affect loading practices, Barden says. “It is essential that the proper teeth and/or cutting edges are installed on the bucket, and the bucket capacity matches the material and machine,” he says.
“The bucket size really depends on the material density that you’re working with,” Morice explains. “Different material densities require different types of buckets and it all goes back to the payload capacity of the toolcarrier. If your toolcarrier has an 8,000-pound load capacity, then you adapt the bucket size to be in line with that capacity.”
Morice says that means using a bigger bucket when working with lighter materials and vice-versa. “Heavier or higher material density requires that you use a smaller bucket,” he says. “A standard bucket is designed for working with material that typically has a density of approximately 2,500 pounds per cubic yard. But if you have to load and carry wet sand, you’re suddenly dealing with a material that can weigh as much as 3,100 pounds per cubic yard. This extra payload with a standard bucket can quickly exceed your machine’s payload capacity, particularly if it is equipped with a coupler. That’s where you get into situations with a tippy machine and you’re not going to be productive working like that.”
Good wheel loader practices apply in load-and-carry applications
To be efficient when digging and loading with a toolcarrier, remember that it is vital to position the truck correctly in relation to the machine. “This limits the amount of carry time needed, which directly leads to better production,” Wolf says. “Having said this, note that it is also possible to position the truck too close to the work zone. Be sure and allow adequate room to maneuver the toolcarrier while positioning the trucks for easy movement in and out of the work area. Optimally, you’ll want to have everything set up so the toolcarrier can load a Class 8 dump truck in three to five passes.”
“A ‘tight vee’ pattern is the best for production loading,” Barden advises. “To use this approach, position the truck so that the toolcarrier can travel a minimal distance (normally from 3/4 to 1 1/2 tire rotations) from the stockpile to the end of its reverse movement away from the pile. Once the toolcarrier is aimed at the truck, it should travel the same amount from the end of the reverse movement to the dumping point into the truck.”
To further increase efficiency, Barden suggests giving your operator complete control of the loading zone. “The guy on the machine should be responsible for positioning (spotting) the truck to load on the driver’s side,” he says. “In other jobsite situations – such as restricted highway or workzone – your crew may have to dictate different loading techniques or place a ground spotter in control of the situation.”
