While there are several criteria that determine the correct attachment for a particular skid steer or CTL, perhaps one of the least understood is hydraulic compatibility. In a recent webinar, product experts at Case Construction Equipment simplified the selection process by educating attendees on the basic hydraulic system considerations.
The process really begins with the hydraulic flow and pressure ratings on both the machine and attachments. Understanding the relationships between flow and pressure is critical when matching attachments to a skid steer or CTL. Start by looking at the fundamentals. “Flow is going to be the speed of the attachment under no restriction,” explains Ted Polzer, director of product and customer support, Case Construction Equipment. If an attachment lists a 30-gpm maximum flow, that is at no pressure or resistance to that flow. “As soon as we start to resist flow, that’s when we start to build pressure. It’s really important to understand what your maximum constraints are for the attachment on the flow and that pressure.”
If you chart flow versus pressure, there is a point where flow and pressure cross to create the most productive setting for a specific attachment. Consider a cold planer. “If you are crowding it too hard and you are running at 3,000 psi, for the sake of discussion, you are going to start generating heat, and you are not helping the productivity of the machine,” says Polzer. “You could be more productive by actually backing off a little bit and reducing some of that resistance to the flow. Your attachment will probably run more consistent with its speed, in addition you’re not fighting that additional heat that is being built in the system. So it’s extremely important to understand exactly what your machine will do and what your attachments are capable of accepting.” This is where a pressure gauge on the attachment can prove beneficial.
Pressure Gauges Can Eliminate Guesswork
“Pressure gives you an idea of how much work you can do,” says Polzer. “One of the training aides that we have used is we simply put a pressure gauge in an area that’s visible to the operator. We mark that and say you’re more productive at this pressure.” This helps eliminate operator concerns. “It is a very inexpensive way to understand exactly where you can be (when operating) and it will drive a lot of consistency with your operators if they are watching that target.” It is worth noting that some of today’s attachments come with a pressure gauge mounted on the attachment clearly visible to the operator.”
Hydraulic horsepower can serve as a good indictor to match machines and attachments in terms of hydraulic system compatibility. This can be calculated by the simple equation hydraulic horsepower = [pressure (psi) *flow (gpm)]/1714. Hydraulic horsepower is good to know because it is essentially telling you what your machine is capable of doing, what your attachment can accept and what kind of productivity to expect. “What’s important about that is many hydraulic attachments are also rated by their hydraulic horsepower.” This is starting to be more common with the newer attachments.