Other than digging, one of the most frequent jobs performed by your compact excavator is lifting. But do you know the proper steps?
Before you start lifting freely suspended objects, let’s begin with the basics.
1. Examining the jobsite and working on slopes
You and your operators are responsible for all jobsites, including lift-related conditions, and need to respond to changes in those conditions that could be potentially hazardous. This can include the machine’s condition, the strength of the surface beneath the excavator and moving with the load. The first step you should take before lifting is to examine the area around the excavator and make sure there is nothing above or below the machine that can cause interference with any objects.
When working on a slope, level the work area if possible. If leveling the work area is not possible, position the excavator with the blade downhill and lowered, and avoid working with the tracks across the slope or swinging the bucket in the downhill direction. Always keep the boom centered and the load as low to the ground as possible to maximize stability. Move as slowly as possible and avoid sudden changes. Never travel on a slope greater than 25 degrees.
2. Understanding excavator lifting capacity
Secondly, understand that an excavator’s lifting capacity is limited by one of two factors: hydraulic limitations or tipping limitations. Hydraulic limitation means the excavator is limited by its hydraulic power to lift a load. Tipping limitation is the point at which the excavator begins to lift off the ground when lifting a load.
Manufacturers test excavators to determine how much weight they can safely lift at various heights and distances from the centerline of the machine. Based on that information, they create lift charts, which are printed in the Operation & Maintenance Manual or posted within sight of the operator, such as a decal in the excavator cab. To maximize the life of the equipment and minimize machine wear, always make sure you and your operators follow the guidelines in the lift charts and do not exceed the recommended lift capacity.
3. Correctly interpreting an excavator lift capacity chart
Although lifting material with an excavator may seem simple, it is important to follow the excavator lift capacity chart, which designates the proper lifting capacity at various lift heights and swing radiuses.
At the top of the lift chart there is information indicating the machine configuration. There may be several lift charts for excavators, based on combinations of boom length, arm length, counterweight size and track shoe width. Some manufacturers will include the bucket size in the lift chart.
If the manufacturer includes a bucket in the lift chart, the company will indicate the bucket’s weight. However, if the lift chart does not include the bucket details, it is up to you and your operators to know how much weight is on the end of the machine. This may include a coupler, bucket, the lifting apparatus itself, and the weight of the material or item being moved. It is important to note that capacities typically marked with an asterisk on the lift chart are limited by the machine’s hydraulic capacity and do not exceed 87% of hydraulic lift capacity, as defined by the International Organization for Standardization (ISO). Rated loads without an asterisk are limited by the machine’s stability and do not exceed 75% of the tipping load.
Next, determine the lift point height, which is typically located in the far-left column on the lift chart. The lift point refers to the distance from the ground to the bucket pin, not from the ground to the object you are lifting. When measuring the lift point height, consider how high or low [below ground] you will need to lift the item, including the height of the item itself, the length of the lifting device and at what height you want to place the item on a transport device.
After determining lift point height, examine the lifting radius from the centerline of the swing point. This distance is typically shown in the top row of the lift chart. Lifting radius is dependent on whether you are lifting over the front of the excavator or squarely over the side. Additionally, if you are operating an excavator with an optional dozer blade, you need to reference the portion of the lift chart that reflects its position during excavation.
Once you have determined the lifting radius, find the cell on the lift chart where the lift point height and radius intersect. The number shown is the excavator’s rated lift capacity in pounds or kilograms. If the cell is blank, the excavator has no lifting capacity at that point, and lifting should not be attempted.
4. Considering pick-and-carry precautions
When traveling or moving an excavator with a suspended load is necessary, it’s recommended to use a safety lifting device, such as an excavator’s lift eye. The lifting apparatus should be approved for the weight of the material and operators should also know how to properly hook the lifting apparatus to the material or object being moved.
Before attempting to pick up and carry a load, align the boom with the forward direction of machine travel. Maintaining this boom position when turning the machine is best for stability. Operators should only turn when necessary, at the slowest speed and with a wide turning radius.
Other factors to consider in pick-and-carry applications include the following:
● Use the shortest lifting radius distance possible.
● Keep the load as close to the ground as conditions will permit.
● Attach strong ropes, otherwise known as tag lines, to prevent the load from swinging back and forth.
● Travel at speeds determined by jobsite conditions.
● Avoid sudden starts and stops.
5. Making use of operator training courses
Some manufacturers, like Bobcat Company, offer mail-order or online excavator training courses, and some equipment manufacturers have in-person training opportunities.
Learning to lift safely is critical for anyone who owns or operates an excavator. Before you set foot on your next jobsite, make sure you familiarize yourself with these proper lifting techniques and ask your equipment dealership what training options are available.
Are you lifting safely? Understand your machine’s lifting capacity to help your life and move loads safely.