Hammer Time

When it comes to demolishing concrete pads, driveways, sidewalks or roadways, contractors have two choices — breakers or drop hammers. According to John Sad, attachment product specialist with the Bobcat Co., choosing which tool to use depends on the goal of the job.

“If a full pad of concrete needs to be demolished, the drop hammer is the perfect attachment,” says Sad. “If there are only certain portions of a pad that need to be removed, a breaker might be better.”

That doesn’t mean that a drop hammer can’t be used on a pad when only part of the concrete needs to be removed. Sad says that if a drop hammer is going to be used in partial pad removal, the concrete should be segregated.

“A drop hammer is indiscriminate when breaking concrete,” says Sad. “If the contractor is using a drop hammer next to concrete that needs to be saved, they must segregate the concrete by slot cutting it before beginning work.”

The thickness of the concrete will determine which tool should be used to slot cut the concrete. A walk-behind saw, a slot cutter and a wheel saw or a planer with slot cut drum should be used to cut a path between the concrete to be saved and the concrete to demolish.

When the decision is made to use a drop hammer, contractors need to size the attachment to their carrier. The rated operating capacity of the machine and the weight of the attachment will determine what model of drop hammer can be used on a carrier. For instance, the Bobcat drop hammer weighs 1,900 lbs, so it can be used on carriers with a rated operating capacity of 1,900 lbs or higher. Most manufacturers of skid steer or track loaders include the rated operating capacity of the machine in the model name. For example, a Bobcat S205 skid steer loader has a rated operating capacity of 2,050 lbs.

Once a drop hammer and carrier have been identified, it’s important to make sure that the attachment is used properly on the jobsite. Properly using a drop hammer begins with maintenance.

Inside the drop hammer is a chain mechanism with a catch. The catch grabs the weight and raises it up. When the chain rotates over the top, the catch falls and releases the weight. The chain in this mechanism should be lubricated before starting work each day. Also inspect the chain tension, the tensioner springs and the tension arms. Sad says that the mounting frame and all welds on the drop hammer should be inspected daily before use for damage or wear. All grease points should receive grease before starting the day’s work.

Keep a look out for drop hammer attachments with unique features like a cushion safety valve, which needs to be inspected daily before use. “The cushion safety valve allows the operator to stop the weight from falling if they decide they don’t want to break concrete in the area they’re working in. If the weight in the attachment is getting ready to drop and hasn’t reached the catch, and the operator decides not to break there, the operator can press the detent switch and the weight will drop slowly,” says Sad.

To make sure the cushion safety valve is operating properly before beginning work, the operator should activate the carrier hydraulics to lift the weight and disengage the hydraulics when the weight is halfway up the cycle. If the cushion safety valve is working properly, the weight will fall slowly.

Once the daily inspections and the lubrication of the chain and greasing are complete, the drop hammer is ready to be used. Sad says that operating the drop hammer properly is just as important as keeping the attachment maintained. “The drop hammer feet should be in contact with the surface when in operation. This will prevent the drop hammer from dry firing, which could cause damage to the attachment,” says Sad.

To move the carrier during operation, Sad says that the feet of the drop hammer should be kept on the ground and the loader should be skidded from side to side or in forward or reverse to change position.

How long it takes to break concrete with a drop hammer will depend on the pounds-per-square-inch rating of the concrete. Thinner concrete will take fewer blows to demolish than thicker concrete. The Bobcat drop hammer has 20 cycles per minute. Sad says that operators will have to develop a feel for when the concrete is demolished. Most of the work the drop hammer performs occurs underground, where operators can’t see.

If any maintenance needs to be performed on the drop hammer, the attachment can remain on the carrier, but make sure the machine is turned off and the hydraulic lines are disconnected. The drop hammer should also be on a level surface when performing any maintenance when it is disconnected from the loader.

For the most part, a drop hammer attachment is a simple machine that won’t require a lot of attention if maintained and used properly.

“A chain that is oiled every day is going to last much longer than a chain that isn’t,” says Sad. “Make sure that the drop hammer is perpendicular to the surface when operating and only move the carrier when the weight is going up. If you do these three things, the drop hammer will have a long and productive life.”

Eric Morse is a public relations manager with Two Rivers Marketing, Des Moines, Iowa.