By Eric Morse
When it comes to creating a flat and dense concrete floor, the tool that serves contractors best is the concrete walk behind trowel. By embedding aggregate and consolidating mortar at the surface, the trowel makes a smooth and dense floor.
Individual contractors have their own technique when operating a walk-behind trowel, however, all contractors should care for their machine in the same way. Maintaining a walk-behind trowel is easy, and a well cared for machine will consistently help contractors achieve results.
Walk-behind Trowel Blades and Float Pans
Key components to a walk-behind trowel are the blades, which are directly in contact with the concrete. Russell Warner, product marketing manager for concrete and light compaction equipment at Ingersoll Rand, says blades are the first components contractors should check before operating the walk-behind trowel. "Make sure the blade arms are straight and not bent, which may cause the blades to wear unevenly," says Warner." The operator should also make sure the blades are pitching at the same rate.
As blades become worn down, the contractor will easily notice. "When the steel starts to wear down, the blade will get thin in some areas and peel back. It looks like aluminum foil or tinsel," says Warner. "When a contractor sees that, it's time to change the blades."
It is crucial to know that even is only one blade becomes worn, all blades must be replaced at the same time to insure consistency on the job, otherwise, it could have a severe effect on the flatness and quality of the floor.
To prevent the lower end from wearing prematurely, blade arms should be greased every 50 hours of use. "Inspect the blade arms periodically to make sure that they don't need grease before the 50-hour interval," says Warner. "That's important because concrete is extremely abrasive and properly lubricating the blades could save money in replacements." Refer to the operators manual for the location of all grease fittings as well as the type of lubricant to use.
So as not to be a hazard, make sure to use only the approved types and properly sized blades for the trowel. All blades should be kept within the protective cage.
Float pans instead of trowel blades have increased in popularity. "Using a float pan requires extra caution because there is increased torque and resistance to the operator," says Warner.
Maintenance Before Operation
As with any piece of construction equipment, there are a number of items contractors should inspect before operating the machine. After inspecting the blades, Warner suggests contractors make sure the emergency stop mechanism is working properly. To do this, put the emergency stop switch in the 'on' position, start the engine normally, and then flip the switch to 'off.' The engine should die immediately. The switch should also move easily between the 'on' and 'off' position [with] no obstructions or friction," says Warner.
Warner notes that some contractors skip this inspection because they've disabled the emergency stop switch. "It is not uncommon for the safety system to be bypassed. That's dangerous. I recommend keeping all manufacturer safety components maintained and running properly," says Warner. If an operator loses his or her grip, the entire walk-behind trowel will start to spin quickly potentially causing an injury.
Engine oil should be checked daily and replaced after every 50 hours of use. Oil in the gearbox should be changed at least once a year.
The air filter should also be inspected before using the walk-behind trowel and replaced as needed. Jobsite conditions will determine how long an air filter lasts. Using the walk-behind trowel on dusty or dirty jobsites will lower the life of the filter.
Check the tension of all belts before using the walk-behind trowel. Belts will stretch due to the tension, and need to be tightened periodically. If the machine has multiple belts, they should all be replaced at the same time. "You want to start with the same size belts and let them stretch together," says Warner. "I also recommend tightening the belts after the first use, to compensate for the initial stretch."
Contractors should periodically check the engine to make sure that it is running at the manufacturer's suggested rpm. "Most lawn and garden stores sell inexpensive tachometers that display engine rpm," says Warner. "Point the tachometer at the spark plugs and read the rpm display. "Always make sure that the engine is set to the manufacturer's recommendations and follow the manufacturer's procedures for adjusting the rpm," says Warner.
Maintenance After Operation
"A clean walk-behind trowel will last longer," says Warner. "Clean the machine thoroughly after every use to clear away all the abrasive concrete from the trowel." Warner recommends using a pressure washer, but to note sometimes concrete will need to be scraped off the trowel. When this is needed, Warner advises contractors to use something like an ice scraper or wooden stake to minimize damage to the paint when scraping.
"I also suggest coating the trowel in some type of form release agent or using one of the concrete cleaning products that are available," says Warner. "Some of the agents are biodegradable products that can be sprayed onto the walk-behind trowel to keep it clean."
The throttle cables, pitch mechanism and engine starting rope should also be kept clean. The throttle cable and the pitch mechanism should be fully lubricated so they move freely. "Because walk-behind trowels are used in abrasive environments, the engine starting rope will see accelerated wear," says Warner.
Many contractors tilt the walk-behind trowel up and hold it perpendicular to the ground to clean the bottom. Warner says contractors should avoid this practice because they risk leaking engine oil and fuel from the machine. Tipping the walk-behind trowel this way could also get oil on top of the piston cylinder causing the engine to possibly lock up.
In the interest of safety, Warner advises contractors to keep the labels on the machine clean and legible. Labels help assist in proper operation and should be visible to anyone who might use the machine.
Storing the Walk-behind Trowel
When it's time to put the walk-behind trowel away for a while, Warner says it should be stored with the blades flat, not pitched.
"If a trowel is going to be stored for an extended amount of time, the fuel should be drained or some type of stabilizer should be added to the tank and carburetor," says Warner. "Store the machine in a protected area, where it is not exposed to the elements, and keep it covered."
Concrete walk-behind trowels are easy to use and simple to maintain. By changing all blades and filters when needed, keeping the machine clean and following the maintenance procedures mentioned above, a trowel will continue helping make concrete floors flat and dense for a long time.
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