Other Publications

Construction Industry Poll

Machine Matters

Machine Matters – March 2009

March 25, 2009 |

The beauty of the medium size skid steer is its compact, muscular performance in small spaces. Mid-size skid steers with a rated operating capacity of 1,751 to 2,201 pounds nimbly maneuver in confined spaces while providing impressive power for digging, lifting and carrying. Your skid steer’s lift arm geometry can be the deciding factor on your machine’s best use.

Skid steer genetics
The key DNA in skid steers is the ability to turn around in their own footprint. Because the left-side drive wheels work independently of the right-side drive wheels, skid steers can perform zero-radius 360-degree turns. This ability is invaluable on jobsites with little room to spare, such as demolition projects, confined space utility construction and moving material around structures and landscaping. The mid-size skid steer’s narrow profile and short stature allow you to work in areas with low overhead clearance and slim access points such as doorways and gates.

Mid-size skid steers produce bucket breakout forces as high as 7,532 pounds on Volvo’s MC80B and offer arm lifting forces up to 6,796 pounds on Komatsu’s SK1020-5 model. The machine’s hydraulic system powers the loader’s lift and drive functions while auxiliary hydraulic systems power attachments. Skid steers that offer high-flow hydraulics can work even harder, running hammers through concrete or drilling through frozen ground. Medium size skid steers can travel at speeds of more than 11 mph. The mid-size skid steers’ wheel base ranges from 40 to 49 inches, making them easy and economical to transport.

Family tree
Medium size skid steers are designed to optimize lifting or reaching. The skid steer family tree branches off at the lift arms. The difference between a vertical- or radial-lift arm configurations is the path the loader arms follow moving from ground level to full reach at maximum height.

Vertical-lift skid steers (sometimes called parallel-lift) lift up-and-out in a straight, vertical line. They maintain their forward reach by rotating the bucket (or attachment) at the joint but don’t move the bucket forward. Additional linkage allows the bucket to pivot, using gravity to keep the face of the bucket consistently level as the arm rises. The vertical lift keeps the load closer to the machine’s body and has a high reach, which can be helpful when lifting loads in areas that don’t allow forward arm movement.

Radial-lift skid steers lift-up-then-out in an arc-motion, starting with the bucket low and close to the skid steer body at ground level, and swinging up and out from the machine’s body as the bucket rises to its maximum height. Maximum reach is at the mid-way point of the arc. Radial lift skid steer arms are connected to the machine with a single pin on each side, so the bucket is in a fixed position and follows the arm’s movement up and out. The bucket’s face generally stays in the position it started in on the ground.
Modifications to these two common lift configurations tend to focus on providing greater reach and stability.

For example, New Holland’s Super Boom vertical configuration lifts the load up and away for maximum reach at maximum height and keeps the bucket level for less spillback. Its low center of gravity reduces tipping and increases lift capacity.
Self-leveling systems on radial lifts use load-leveling sensors to continuously monitor and adjust the bucket to keep it level.

Individual skills
Both vertical-and radial-lift arm machines will move and carry material around your jobsite, but each style has its own advantages.