FEATURES
Developments in Topdresser Technology

by Bruce Carmichael

Design changes enhance performance

Today’s topdressers are light, efficient and environmentally friendly, while requiring less maintenance than older designs. Photos courtesy of TrynEx International.

Topdressing has been evolving since the early days of golf. What began as a generous application of sand that was applied only a couple of times each year, has developed into a process that is practiced more frequently with a precise amount of material. Proper equipment is needed to adhere to these recommendations and, fortunately, manufacturers have adapted with the times to maximize the accuracy of their machines while minimizing the physical footprint and eliminating unnecessary maintenance.

While several types of topdressers are available, from large units capable of tackling par-5 fairways to small walk-behind machines, we’ll focus on the small, towable units. These are large enough to improve efficiency over walk-behind equipment, but gentle enough to handle topdressing applications on greens and tees.

On target

The United States Golf Association (USGA) has been recommending lighter applications of topdressing material, and some superintendents are spreading sand at only 1/32 of an inch. To maintain such a light depth in a uniform application, a topdresser’s feed system, gate, spinner and controller all must work together to achieve results that are on target with individual needs.

The traditional method of feeding material to the spinner is a conveyor system, which is used to move material from the hopper, through the gate and onto the spinner. This system works well in high-capacity units, where a wide belt is capable of moving large amounts of material from the hopper, but where conveyors excel in quantity, they lack in consistency.

Manufacturers have recently developed auger systems, which feed a more accurate amount of material onto a precise spot on the spinner. With the help of a digital readout, the operator is able to see exactly how many pounds of material he is spreading per minute according to the auger speed setting. This technology has increased in popularity not only for its consistent, measurable material flow, but also for its ability to handle diverse materials, rather than just sand. However, since the auger diameter used in these units is typically 6 to 7 inches, they don’t have the capacity to deliver as much material as large conveyors.

Material waste is another important consideration in many new designs. In order to reduce material waste upon start-up and shutdown, some manufacturers have developed an automatic procedure for when the unit is turned on and off. When all topdresser components are shut off at the same time, a buildup of material is typically left on the spinner. Then, when the unit is started, the operator experiences a sudden rush of material that leaves a clump of sand on the ground. To prevent this and keep the system cleared at all times, some machines will automatically power up the spinners before the feed system starts, and then shut the spinners off a few seconds after the material flow stops.

Spinner enhancements have been developed to help accommodate personal preferences. These include tiltable spinners, which help control how material is propelled into the turf canopy. Also, some designs incorporate spinners with adjustable paddles to further fine-tune the spread pattern.

Even the gate plays an important part in the feeding process. It helps regulate material flow, and in some topdressers it can be electronically actuated from the seat of the towing vehicle. The positive locking feature on these electronic units is especially handy for quickly closing and opening the gate when moving from one green to the next. This prevents material from bouncing out during transport.

Regardless of the feed system used, any topdresser can be inhibited by material that lumps together, especially wet sand. This prevents a consistent flow of material to the spinner, reducing the accuracy for which superintendents strive. However, many units now contain vibrators to eliminate the problem by breaking up such material.

The latest controller technology allows a topdresser to spread accurately and helps to prevent material waste. Features like tiltable spinners and adjustable paddles help to fine-tune the spreading pattern. By going to a completely electric-powered unit, superintendents may eliminate the need for maintenance on the drive system.

To manage all of these components, controllers have started to become more sophisticated. Like the topdressers themselves, controllers come with varying abilities, from basic to more advanced. The simplest machines may require the operator to make adjustments on the machine itself, which can become difficult when trying to pinpoint the desired settings. By using the latest technology, the operator can mount electronic controls in the towing vehicle and manage each of the components independently from the cab. The industry is beginning to trend toward the technology of independent controls, which allows a topdresser to spread accurately and helps to prevent material waste.

Driven to succeed

Not only has the industry seen advancements in feed designs, but the drive systems that power them have also improved. Because of these changes, the environmental issues associated with traditional topdressers have been diminished.

Until recently, most topdressers were driven by an independent hydraulic system, but the big push to go green has changed the way superintendents think when purchasing equipment. They’re beginning to favor self-contained equipment or avoiding hydraulic systems altogether in order to help prevent the spill of hydraulic oil. This is an especially important consideration on greens, which can be severely damaged by a breach in a hydraulic hose.

The trend is going toward electric equipment and away from gas-powered hydraulic systems due to the pollution caused by running an extra engine. In fact, the Environmental Protection Agency states that an engine found in a walk-behind mower (which typically has about half the horsepower of a topdresser engine) can produce as much pollution in one hour as 11 late-model cars.

Lighten up

Besides protecting greens and tees from environmental hazards, superintendents are also concerned about weight issues. If a golf ball can leave a mark after landing on a green, imagine what a half-ton, 1.5-cubic-yard topdresser could do. Manufacturers listened to this concern, however, and have worked to design lightweight machines; this is largely done by increasing the surface area of the machine’s contact with the ground and reducing the overall weight of the unit.

To spread out a machine’s weight over a larger surface area, all topdressers use a similar type of wide turf tire. However, the biggest breakthroughs in reducing a physical footprint come in the weight reduction techniques by manufacturers. Obviously, the weight of material in the hopper cannot be reduced, but lightweight drive systems and hopper designs can make a huge impact in weight reduction.

As mentioned, hydraulic systems raise environmental concerns on the golf course, but they also increase the weight of a topdresser. The hydraulic fluid alone can contribute more than 75 pounds to the machine. If the hydraulic system is powered by a separate gas engine, significantly more weight is added. Some manufacturers have eliminated the engine weight by designing their machines to hook up to the towing vehicle’s central hydraulic unit, but on some new models, all hydraulic components have been replaced with a lighter, simpler electric motor.

Hoppers constructed of lightweight materials, such as poly, help to lessen the physical footprint of topdressers.

Some manufacturers are also taking advantage of lightweight hopper designs. They’re looking beyond steel to materials like polyethelene. Although poly weighs much less than steel, it still maintains the durability needed in a topdresser.

Maintenance

The remaining development in topdresser technology is reduced maintenance. Since superintendents would rather spend time taking care of their turf and not their equipment, they look for machines that require little service.

One of the biggest maintenance requirements of a topdresser comes from the conveyor. This system needs periodic adjustments to keep the belt at its correct tension, and there are multiple moving parts that require regular greasing. Beyond scheduled maintenance, some have experienced issues with material working its way underneath the belt and eventually binding up the conveyor.

The drive system needs service checks of its own. Independent hydraulic systems require filter and fluid changes, plus the repair of damaged or worn components. The small engine that powers the hydraulic system also has a separate maintenance schedule, which includes oil changes, filter changes, spark plug replacements, etc.

By using the central hydraulic unit of the towing machine, superintendents reduce the number of hydraulic components to maintain. By going to a completely electric-powered unit, they virtually eliminate the need for service on the drive system.

In a way, the trends in topdressers closely mirror those of most machines, from automobiles to lawn mowers. Many of the new models are light, efficient and environmentally friendly, while requiring less maintenance than older designs. As intelligent engineering meets the growing demands of superintendents and turfgrass maintenance, we’ll continue to see new improvements in these machines, as well.

The author is TurfEx national sales manager for TrynEx International.