Bobcat Packs More Work into Smaller Skid Steer

Sept. 28, 2010

Judging the S630, a skid steer of 2,180 pounds rated operating capacity from Bobcat’s all-new M Series line, is harder than it looks. It fills a hole in the Bobcat line, so there is no direct comparison in the line against which its performance can be compared. It is the first of what Bobcat is calling a completely “new generation” of skid steers – skid steer 2.0 – yet most of the changes are measured in inches.

Judging the S630, a skid steer of 2,180 pounds rated operating capacity from Bobcat’s all-new M Series line, is harder than it looks. It fills a hole in the Bobcat line, so there is no direct comparison in the line against which its performance can be compared. It is the first of what Bobcat is calling a completely “new generation” of skid steers – skid steer 2.0 – yet most of the changes are measured in inches.

A Field Test was clearly necessary to see just how much productivity and efficiency these revisions might deliver. After much discussion, we decided to pit the S630 against the S220, a loader with slight advantages in operating capacity and horsepower on a larger frame.

Basic dimensions of the S630 do suggest a rethink of the skid steer concept by the company that invented them. Bobcat loader specialist, Mike Fitzgerald, told us customers continue to call for more working capability in smaller spaces. The S630 demonstrates the Bobcat approach to that engineering challenge.

It starts with a shorter frame – a shorter skid steer can maneuver in smaller areas. The S630 is more than six inches shorter than the S220. The M Series also revived a shorter wheelbase that the company hasn’t used since retiring the 863 in 2004. Shorter wheelbase allows the machine to skid through turns a little more easily.

But engineers obviously set their sights on a small machine that can work big. The S630 has almost the same engine horsepower as the S220 (74.3 and 75, respectively). About 225 pounds more operating weight brings the S630 to within 20 pounds of the S220’s 2,200-pound rated operating capacity. But perhaps the greatest productivity boost is designed into the hydraulic system. Bobcat raised the operating pressure to 3,500 psi (a 200-psi increase) and added 2.3 gallons per minute of flow to equip the S630 with 18 percent more standard hydraulic horsepower than the S220.

The most visible change is in what Bobcat is calling a “cab-forward” design. While it’s not initially obvious that Bobcat moved the cab forward, the rear does look longer. The cab was only moved ahead two inches, and the S630’s frame is six inches shorter than the S220’s. So there is actually less machine for the operator to look over behind the cab. Fitzgerald says this improves visibility to both the front and rear of the machine.

It’s not until you’re in the seat, with a bird’s-eye view of the attachment, that it becomes obvious the cab has been moved forward. Combined with significantly increased glass dimensions, the view to the ground all around the working end of the machine is improved.

“You can look down and see the inside and the outside of your tires,” says Ras Rambough, one of our two test operators and a construction veteran who runs the soil-screening operation for Grand Forks’ Opp Construction. “If you’re going along the edge of some lady’s flower bed, it’s going to be easy to stay out of her flowers.”

The new cab-door sill is lowered for better view and easier entry. The windshield-washer reservoir has been moved off the door. Frameless glass expands the view to the bucket cutting edge and the ground around the attachment.

For our Field Test, Bobcat made available an S220 and S630, both with enclosed cabs, standard hydraulic controls, and bias-ply tires. Both machines were new – the S220 started the test with 10.8 hours on the meter and the S630 had 7.4 hours.

We figured a task that required digging, a bit of carrying, and then loading a truck would compare the unit’s overall performance, but Bobcat’s hydraulic-system choices really piqued our curiosity about productivity with hydraulic attachments.

Higher hydraulic pressure would boost horsepower across the board, but it was an interesting engineering choice to field the S630 with 30.5 gallons per minute (gpm) capacity in high-flow mode. The S220 high flows 37 gpm, giving it a more than 14 percent advantage over the S630 in high-flow mode.

Our test operators took turns pulling 100-foot stretches of trench with a Bobcat LT405 high-flow trencher. Once the trencher was in the ground, we gauged the angle to make sure it was at 45 degrees, and then started the stop watches. Trenches were consistently 32 inches deep. Each operator made two runs with each loader and the high-flow trencher. Times came in consistently at 23 and a half minutes for each 100-foot trench. Despite its disadvantage in hydraulic horsepower, the new S630 kept up with the S220 at 4.3 feet of trench per minute.

Bobcat’s marketing suggested that the M Series’ simplified hydraulic circuitry would make enough flow available at the attachment to compensate for the difference between the two machines’ hydraulic horsepower. Our tests indicate that they are right.

“This is some of the hardest digging you’re going to find, and the ’630 didn’t get near stall-out. It seemed to pull through better even though it didn’t have the higher rating,” says Ted Fey, our other test operator and a supervisor with Opp Construction. “There seemed to be more of a direct communication between the hydraulics and the engine – you knew before it actually started to pull down that you had to let off a little bit to keep your flow going. You could hear it in the engine rpm, whereas the other one you never really heard the engine losing the pressure.”

Other soft issues also contributed to the S630’s high-flow production.

“I like the instrumentation on it (the S630) a lot better,” says Fey. “It’s electronic, but it comes up like the old-style dials where the other one just has bar-graph displays. It’s an individual preference but I could monitor the engine rpm on this one so much easier. If you start binding the trencher a little bit you can easily look and see if it’s pulling down the engine or not.”

Confirming the trencher results were no fluke of operator style or the experience, the S630 and S220 tied the auger test in high-flow mode, too. We timed the operators boring 16 four-foot holes with a 16-inch auger, five feet apart. They both finished just more than two holes per minute.

The final test of the first day had us measuring a pair of 80-foot runs for the digging and loading event as the wind dampened. Each operator would dig up a bucket load of undisturbed turf and soil, carry it at best possible speed around a cone 80 feet from the digging and loading area, then return to dump the bucket into a waiting truck. With five bucket loads on board, we’d weigh the trucks.

The Dakota wind had begun driving an easy drizzle. With two trucks and tests on both loaders going simultaneously, conditions for each machine were pretty well matched even as they slowly degraded. The rain never intensified, but poor traction definitely challenged the loaders’ ability to bust sod.

Our operators took a little longer filling the S630’s bucket – the S220 was able to load the truck in about 7 minutes 4 seconds, while the S630 averaged 7:32. It’s possible that keeping all four tires on the ground and pulling in a short-wheelbase machine is a skill that would take a little more practice for our operators to master.

Despite the slippery digging surface diminishing the S630’s promised 15- to 20-percent tractive advantage, the new machine did dig more dirt. Its average load was 7,470 pounds, about 7 percent more than the S220 produced. The result was another tie, this time at 29.7 tons per hour.

The afternoon’s rain turned to a mid-October snow, and Fey drove onto the fairgrounds the next morning with three inches of the white stuff melting off his truck. Luckily, Bobcat rents the riding arena at the Fargo fairgrounds during winter for demonstrations and testing. We were limited to 50-foot runs to avoid the building’s foundations, which was fine since the last attachment test would use a Model 313 standard-flow trencher. Again, each operator cut two trenches with each machine.

In standard-flow mode, the horsepower shoe is on the other foot – the S630 delivers 11 percent more hydraulic horsepower than S220. The S630 cut 50 feet of 24-inch-deep trench in an average of 12 minutes and 5 seconds, while the S220 would require a full 2 minutes longer. The new M Series contender finished the test with nearly a 14-percent productivity advantage over the S220.

Fey and Rambough did some work with a pallet fork and a load they could place on the bed of a drop-sided truck and a low-bed trailer, to compare pallet work with the new and old machine (more than half of skid steers sold today go out with pallet forks). Both machines performed well.

“This one (the S630) had better visibility just a little bit higher, where we were loading the truck,” says Fey. “We do more truck loading anyway, so for me it was the better machine of the two for pallet loading.

“The fork levels better, too,” he adds. “It holds the forks more at a uniform level when you raise and lower the loader arms.”

The final Field Test stop was back at the fuel bulk tank. The S220 topped off with 12.3 gallons and its hour meter showed 4.8 total hours of work since the start of our testing. The S630 had burned 12.5 gallons in 4.6 hours. Having burned 2.6 gallons of diesel per hour, the S220 showed a 6-percent fuel efficiency advantage over the S630, which burned 2.7 gph.

“That’s not bad,” says Bobcat’s Fitzgerald. “The S630 had to work harder to keep up with the S220 in high-flow trenching.”

The S630’s fuel economy would likely be better in standard-flow work, and our testing suggests it can trench at standard flow rates nearly 250 feet of 24-inch trench per hour compared to the S220’s 215 feet.

The S630’s 74.3 horsepower diesel engine mandates that it meet Tier 4 Interim emissions limitations, whereas the S220, barely over EPA’s power break at 75 horsepower, can remain at Tier 3 until 2012. Kubota’s Tier 4 Interim engines give up a little fuel efficiency to their Tier-3 counterparts, so a comparison between the S630 and a hypothetical S220 with T4i engine would likely yield some fuel-efficiency advantage for the S630.

“You could tell that the 220 had a little bit more power when you’re running it, but from the operator standpoint, there’s just no comparison between the two machines,” says Fey. “This one’s (the S630) just so operator friendly. There are several changes they made that you can’t figure out why they didn’t do it years ago.”

AugeringAugeringS220S630Holes/minute2.22.3 (+ 4.5%)Test SetTest SetS220S630* Manufacturer’s suggested retail price, as testedRated Capacity2,200 lbs.2,180 lbs.Weight7,483 lbs.7,707 lbs.Horsepower7574.3Hydraulic pressure3,3003,500Hydraulic Flow(standard)20.7 gpm (39.9 hp)23 gpm (47 hp)(high flow)37 gpm (71.2 hp)30.5 gpm (62.3 hp)Length142.9 in.136.8 in.Wheelbase48.4 in.45.3 in.MSRP*$44,524$43,180TrenchingTrenchingS220S630High Flow (32 in.)4.3 ft/min4.3 ft/minStandard Flow (24 in.)3.6 ft/min4.1 ft/min (+ 14%)LoadingLoadingS220S630AVG time7:047:32 (+ 7%)AVG load6,9807,470 (+ 7%)Tons/hour29.629.7