Choices abound in the skid-steer loader market and a vast amount of information is available to contractors, detailing each model. Caterpillar has offered some key considerations contractors should take note of when choosing a skid-steer loader.
Rated Operating CapacityRated operating capacity (ROC) is a stability measurement by which skid-steer loaders are rated and compared. ROC is calculated as 50% of the machine’s tipping load. The tipping load is the amount of weight that would lift the rear tires when applied to the bucket at the machine’s maximum reach-point in the lift cycle.ROC is important to consider, but it has nothing to do with the breakout and lift force capabilities. Machines with equal ROC may have completely different breakout and lift force capabilities.
Engine HorsepowerBuyers often look to net engine horsepower in order to determine or compare the machine performance level. Engine horsepower alone is not a good indicator of performance, and it has little to do with ROC and breakout or lift forces.Other factors like inefficient hydraulic systems, machine weight, wheelbase, machine balance, and axle torque could have significantly more impact on a machine’s performance over a few horsepower.
Manufacturers often increase machine horsepower in order to overcome inefficiencies such as weight, balance, or inefficient drive pumps or motors in machine design.
Hydraulic HorsepowerWith skid-steer loaders, the ability to run hydro-mechanical work tools effectively using the hydraulic horsepower may take priority over engine horsepower because the tools are hydraulically run. Engine horsepower generates drawbar horsepower in the drive circuit and implement pumps. Those pumps and circuits generate hydraulic horsepower to run work tools.Engine horsepower is needed when the machine multitasks, using drawbar and hydraulic horsepower at the same time. When quoting a machine, it’s important to have competitive horsepower ratings if the machine will be running hydro-mechanical work tools.
Contractors should consider the type of pump the high-flow system is using. Most high-flow systems are designed by adding a gear pump to the standard flow circuit to add incremental flow at the same system pressure as the standard system. This increases the available hydraulic horsepower by increasing the speed of the work tool, but it will not provide additional torque to the work tool.
Additional torque would require the high-flow system to provide higher system pressure, too.
Variable-displacement piston pump high-flow systems are currently the only such systems that provide higher system pressure.
Lift Pattern and LinkageContractors should also consider the lift pattern and linkage of the machine they are buying. Two types of lifting arrangements are available on skid-steer loaders—radial and vertical lift. Radial lift has one pin joint in the rear tower of the machine. It raises and moves in an arc or radius fashion (hence the name). The benefits of the radial lift pattern are strength and durability of the linkage at mid-lift.Vertical lift machines maintain a more vertical lift path from the bottom of the lift cycle to the top thanks to the four-bar parallel lift linkage system.
These machines can generally reach higher lifting heights and have extended bucket pin reach at the top of the lift cycle, increased dump angles, and higher ROC from a smaller, lighter machine.
Since manufacturers have different designs for vertical lift machines, maximum hinge pin/bucket pin height and the maximum dump angle should be compared.
Both of these dimensions can affect the true reach and dump height capabilities of the machine. A less-effective dump angle can increase the reach spec, so bucket pin height and reach are more comparable.
—Information provided by Caterpillar. For more information about Caterpillar skid-steer loaders, visit www.cat.com.
