Topdressing - down to a science?

Pairing tradition with technology, groundsmen combine their experience with the latest industry trends to maintain a picturesque turf. Education is a must to keep up with the latest research findings in the business. And, as groundsmen adapt to new turf and grass recommendations, equipment manufacturers try to stay par for par by incorporating new technology in their latest designs of turf maintenance machines.

Of all these turfcare trends, topdressing is one that has been evolving since the early days of golf. What began as a generous application of sand, which was applied only a couple times each year, has developed into a process that is practised much more frequently with a very precise amount of material. Proper equipment is needed to adhere to these recommendations and, fortunately, manufacturers have adapted with the times to maximise the accuracy of their machines, whilst minimising the physical footprint and eliminating unnecessary maintenance. One could say they have the design of topdressers down to a science.

Whilst several types of topdressers are available - from large units capable of tackling par-five fairways to small walk-behind machines - we'll focus on the small towable units. These are large enough to vastly improve efficiency over walk-behind equipment, but are gentle enough to handle topdressing applications on the most precious areas: greens and tees.

On Target

The United States Golf Association (USGA) has been recommending lighter applications of topdressing material and, over there, some groundsmen are spreading sand at less than 1mm. 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. Just as the name hints, a conveyor 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.

Recently, manufacturers have 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 his 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 pure sand. Since the auger diameter used in these units is typically 150 to 180mm, they don't have the capacity to deliver as much material as large conveyors, though.

Material waste is another important consideration in many new designs. Again, auger feed designs excel in this category, as conveyors have a tendency to drag sand underneath the machine and spill it onto the ground. But, in order to reduce material waste upon startup 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 build-up 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 occurrence, 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.

Next, a few 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 for further fine-tuning 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 occurrence prevents a consistent flow of material to the spinner, reducing the accuracy for which greenkeepers strive. However, many units now contain vibrators to eliminate the problem by breaking up such material.

Finally, 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 becomes difficult for pinpointing the desired settings. But, 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 have been driven by an independent hydraulic system but, just as in every other industry, the big push to go green has changed the way groundsmen think about purchasing equipment. They're beginning to favour 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 petrol or diesel-powered hydraulic systems due to the pollution caused by running an extra engine. In fact, the Environmental 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 eleven late-model cars. So, by going to an electric motor, many are eliminating the risk of hydraulic oil spills, lowering their fuel consumption, reducing emissions and experiencing quieter operation since there is no longer the noise of a small engine.

Lighten the Load

Besides protecting their greens and tees from environmental hazards, greenkeepers and groundsmen are also concerned about weight issues - and for good reason. If a golf ball can leave a mark after landing on a green, imagine what a half-ton topdresser could do! Manufacturers have understood this concern, however, and work hard to design lightweight machines.

Let's start by examining how manufacturers have taken strides in reducing the physical footprint. This is largely done by two methods:

1. Increasing the surface area of the machine's contact with the ground
2. 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 tyre. 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 - without leaving an impact on the ground.

As mentioned, hydraulic systems raise environmental concerns on the golf course, but they also increase the weight of a topdresser. Just think - the hydraulic fluid alone can contribute more than 34kg to the machine, and, if the hydraulic system is powered by a separate petrol 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, even more, new models have replaced all hydraulic components with a lighter, simpler electric motor.

Also, some are beginning to take advantage of lightweight hopper designs. They are looking beyond steel to new materials like polyethelene. Although poly weighs much less than steel, it still maintains the durability needed in a topdresser.

Take Care

The remaining development in topdresser technology is reduced maintenance. Since greenkeepers and groundsmen would rather spend time taking care of their turf and not their equipment, they increasingly look for machines that require little service. Again, manufacturers understand this fact, so they adapt to this demand as well.

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.

Additionally, 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, just like all other engine-powered equipment in a greenkeeper's or groundsman's repertoire. This includes oil changes, filter changes, spark plug replacements, etc.

Due to the amount of time regular maintenance consumes, many have adopted the principle of KISS: Keep It Simple, Stupid. In other words, they have been demanding new equipment that can deliver the productivity they need, but with fewer moving parts to maintain.

One way that some are doing this is to avoid independent hydraulic systems. By using the central hydraulic unit of the towing machine, they reduce the number of hydraulic components to maintain. And, by going to a completely electric-powered unit, they virtually eliminate the need for service on the drive system altogether.

As mentioned, many are starting to use topdressers constructed with lightweight materials, such as polyethylene. Not only are these new materials lighter than steel, but they also eliminate corrosion concerns. For example, steel units need to be washed out regularly and require touch-ups when the paint is scratched. If the exposed metal is not taken care of, rust will occur. Poly, on the other hand, does not need such care.

In a way, the trends in topdressers closely mirror those of most machines, from cars to lawn mowers. Many of the newest models are light, efficient and environmentally friendly, while requiring less maintenance than older designs. Topdressers are certainly no exception. As intelligent engineering meets the growing demands of groundsmen and turfcare maintenance, we'll continue to see new improvements in these machines as well.

With thanks to Steve James, Sales Manager, Broadwood International.
Tel: 01420 478111
Email: info@broadwodintl.co.uk www.broadwoodintl.co.uk