Walk-behind concrete saws come in a range of sizes, from compact 4- or 5-hp electric-powered models up to large, diesel-powered pavement saws boasting 65 hp or more. Determining which size will be most productive for a particular cutting task largely comes down to the length and depth of the cut, and the material your customers will be cutting.
Yet, selecting a saw is not that simple. Jobsite conditions and specifications, as well as the features of the saw itself, can influence which size and type will deliver the most cost-effective cutting performance.
Entry level saws
"Entry level" saws (13 hp and below) are typically found on projects requiring shorter cutting lengths and shallow cutting depths.
"The smaller saws, like our CS1 entry level model, are great for patch work, small jobs, restoration," says Ed Varel, engineering project manager, Stone Construction Equipment. "You could use it on large expansion joints. But with a smaller saw, you run the risk of not keeping a straight line because you have more influence over the saw than the saw does over the cut."
Saws in this size class are well suited for residential applications, such as driveways or patios, as well as sidewalks and walkways. They are also a good choice for indoor applications, where their compact size and easy maneuverability can be an advantage.
The option of an electric motor in place of an internal combustion engine can also be an important consideration, particularly in confined areas with poor ventilation.
Another advantage of small saws is transportability. "With a small saw, two guys can put it in the back of their pickup truck and drive out and do the cut," says Richard Tremain, product manager, Husqvarna Construction Products. "Whereas, with a 35- or 65-hp saw, they're going to have to load it up on a specialized truck or trailer for transporting it out to the job."
Units rated at 13 hp or less generally come standard as push saws, with optional self-propelled capability on certain models. According to Tremain, the decision to add the self-propelled option comes down to economics and the job size. "If you were going to cut eight hours a day and you wanted to be more productive and not fatigue the operator as much, you would want to go with a self-propelled saw," he states.
As the number, length and depth of cuts increase, so do the power and size requirements for the saw.
"As a general rule of thumb, if your customers are going to cut more than 4 inches deep three or four days a week, then you would want to look at the 35- to 65-hp saws," says Tremain. "The larger horsepower is when you start with the professional guys who cut concrete everyday for a living."
According to Brenda Nabarrete at Soff-Cut, mid-size saws (roughly 13 to 35 hp) are well suited for use on small to medium-sized commercial slabs. "The larger saws are designed for big slab pours, or for decreasing the amount of time it takes to cut a slab," she adds.
Diesel power becomes available as saws go up in size. "The advantage that diesel engines have is their torque — they have a lot more than a gas engine," says Tremain. This can have a significant influence on the saw's ability to hold the blade at the required rpms under full load.
Of course, the saw must be able to effectively transmit that power to the blade, regardless of engine type. To maximize this power transfer, Husqvarna has introduced a right-angle gearbox on its larger models.
"Instead of mounting the engine transversely on our large saws, we mount it in line and we put the right-angle gearbox on the front with two output shafts," Tremain explains. "We're able to put 16 pulleys down to the bladeshaft — eight on each side — and we're able to transmit more horsepower from the engine to the bladeshaft." For example, the new 48-hp Target Pro 48 is capable of transferring 42 hp straight to the blade.