Comparing rotary-riding mower components

Fast, uniform cutting is the name of the game with rotary commercial riding mowers, whether they are zero-turn-radius units or rear-wheel-steer types. Every manufacturer is out to produce a durable machine that creates a good, quick cut. Most of their machines are similar. Many manufacturers, in fact, use the same engines and hydrostatic transmissions, similar steering systems and deck designs and the same serviceability features. However, components of different models and types vary.

Hydrostatic transmissions: variations on a theme Most manufacturers incorporate a hydrostatic transmission in their commercial mowers. Similar to automatic transmissions in automobiles, they allow smooth variation of speed via foot pedals or hand levers without requiring you to manually change gears. The majority of zero-turn-radius models feature two separate hydrostatic drives on independent axles. This allows one wheel to go forward while its counterpart stops or reverses.

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Ferris Industries (Munnsville, N.Y.) uses a variable displacement hydro-drive system with hydro-gear pumps and Ross wheel motors on its midmount ProCut Z zero-turn rotary. Additionally, they use an independent drive system (IDS) that utilizes two separate reservoirs on the hydraulic drive to prevent cross-contamination.

Snapper Inc. (McDonough, Ga.) incorporates Eaton hydrostatic transmissions with integrated gear reduction on all its commercial zero-turn-radius riding mowers. "We use Eaton because they are a one-piece unit," says William Lowe, marketing product manager at Snapper. "There are a variety of units available that use a hydrostatic pump bolted to a gear box. The pump runs a hydraulic wheel motor with multiple components. Instead, ours is an integral unit with a hydrostatic pump built in and a gear drive built in-the wheel bolts right on the end of the axle. They have fewer parts and pieces."

Similarly, Walker Manufacturing Company (Fort Collins, Colo.) also uses dual, sealed independent hydrostatic, transmissions for its zero-turn units. Tim Cromley, Walker's marketing and customer-service representative, explains that the hydrostatic transmission directly bolts to the gear case providing a completely sealed and maintenance-free drive unit.

The Toro Company (Bloomington, Minn.) uses a different type of integrated hydrostatic transmission for its rear-steer, out-front commercial riding rotaries. The Groundsmaster 3000 series have a Sauer-Sundstrand integrated hydrostatic transaxle (IHT). This incorporates the hydrostatic transmission, mechanical gearbox, differential, drive axle, power-take-off system and hydraulic-system pump and reservoir in a single component.

"Typically, the transmission, front drive axle and PTO system are three separate parts, which need to be maintained by the customer. This integrates all three functions and eliminates a lot of the servicing-especially on the PTO system," says Rich Guertin, principal design engineer at Toro.

Hustler/Excel Industries (Hesson, Kan.), offers dual hydrostatic traction-drive systems on its 3000 series rear-steer units. "This innovation was just introduced this season," says Jeff Alfaro, marketing manager at Hustler/Excel. Hustler's new 3000 Series includes zero-turn and rear-wheel-or optional all-wheel-drive models.

John Deere (Raleigh, N.C.) offers hydrostatic transmissions on their zero-turn and rear-wheel-steer riding rotary mowers, according to Gregg Breningmeyer, Deere's manager of market development for worldwide commercial-mowing products. The zero-turn mowers use dual Eaton hydrostatic pumps. The larger rear-wheel-steer front mowers use Yanmar hydrostatic transmissions with a patented two-pedal foot-control system. Deere's two-pedal system allows you to press one pedal to move forward and the other to reverse the unit.

Conversely, Kubota Tractor Corp. (Torrance, Calif.), features a single-pedal-operated hydrostatic transmission for direction changes on its F60 series front-mount mowers. Kubota's F60 series also features auto-assist 4WD with a dual-acting overrunning-clutch system. In forward or reverse, the overrunning-clutch system automatically transfers power to all four wheels when needed, thus eliminating wheel spin.

Steering mechanisms: joystick, twin-lever and wheel According to Mike Kadel, marketing manager at Dixon Industries Inc. (Coffeyville, Kan.), about 75 percent of zero-turn-radius machines steer via twin levers. Dixon's ZTR 5022 uses twin-lever steering, as do models made by John Deere and Ariens Co. (Brillion, Wis.). Lesco, (Rocky River, Ohio), uses twin levers on its mid-mount Viper zero-turn model. All Encore zero-turn-radius models use twin levers while the Grasshopper Co. (Moundridge, Kan.), puts them on its out-front zero-turn-radius Mid-Size 600 series and out-front Gemini 700 and 900 series. "We did a lot of customer-feedback analysis in trying to identify a number of different applications for steering mechanisms for zero-turn-radius mowers," explains Deere's Breningmeyer. "The feedback we got overwhelmingly indicated that customers preferred the two-stick-type application. I think that was driven by the familiarity the customer has with that type of operation."

Some zero-turn models operate with a single-lever joystick. Hustler's zero-turn-radius Model 3300 uses a single lever it calls "trim steering." Most of Snapper's zero-turn-radius mowers use joysticks, including models ZM2500KH, MZM2200KH and the ZF2300GKU. "We have chosen joysticks because one-hand operation is simple, convenient, easy to use and less fatiguing. In addition, it makes it easy to explain. It is point-and-go steering," explains Snapper's Lowe.

Some models use other steering mechanisms. Hustler's 3000 series features the company's recently introduced H-bar steering. H-bar steering (similar to motorcycle handles and throttles) is self-centering and provides independent control of each drive wheel. You control speed, direction, braking and turning with the T-shaped H-bar. Rotating the handle grip activates the throttle (eliminating the need for foot pedal). You make turns by pivoting the handle, like a motorcycle. "We believe the advantage over the twin-lever steering is that you have a reference point when you are handling the equipment. [With twin-lever], when you go forward, you have to extend your arms out, so you are running the entire day with your arms extended. [With the H-bar Steering], it is in front of you, and you can rest your arms on the armrests and simply rotate the handle," Alfaro says.

Walker uses two levers on its zero-turn-radius mowers. "What makes our system unique is that pushing forward on the levers does not move the mower," Cromley explains. "Only pushing forward on the forward speed control, (a third lever) to the right of the operator seat, starts movement. If you want to turn right, you would slow the speed down on the right wheel by pulling back on the right lever. You also can lock the levers in place using a friction lock for a cruise-control effect."

Four-wheel-drive and rear-wheel-steer units with "traditional" steering wheels are manufactured by Ransomes and Jacobsen (both divisions of Textron Turf Care And Specialty Products, Racine, Wis.), as well as Kubota Tractor Corp., John Deere and The Toro Company.

"[A steering wheel] is easiest to understand, operate and become accustomed to," says Toro's Tim Koch, marketing manager for riding rotaries. "End users such as municipalities or park districts prefer the steering-wheel models because operators typically do not need extensive training to drive them," he says.

John Deere's rear-wheel-steer products incorporate a power-steering system that has a minimal amount of wheel turns from lock to lock, according to Breningmeyer. "Most Deere mowers have only one-and-a-half to two turns from lock to lock, which provides maneuverability and reduces operator fatigue," he says.

According to Ferris' product specialist Roy Dust, "roughly eight years ago, we went from bushings to bearings in the tail steering wheel of our 3-wheel riders. Over the years, we've increased the rear steering tire size and the strength of our rear-steering yoke."

Decks: a cut above Decks are made of steel in the commercial-rotary-riding market and can be either fabricated (made of steel plates welded together), stamped or a combination thereof. Rotary-riding-mower decks come in myriad sizes ranging from 36 inches up to 96 inches or more.

Toro offers welded-construction, impact-resistant decks. "The decks are as beefy as any component we put into the product," according to Koch. Guertin adds, "When Toro tests its deck designs for durability, they use calculations, but they also apply a brittle lacquer coating to the decks." Koch says, "The lacquer is called stress coat and it provides important developmental data when it cracks in high-stress areas of the deck during testing. This allows our engineers to improve the design."

Various manufacturing engineers also use strain gauges with data recorders in the field to measure the stress on the steel decks. They then go back to the lab, apply the loads, measure the strain levels and redesign the product if necessary. This testing guides the overall design and placement of reinforcement plates.

"The smaller-sized Toro decks use 12-gauge housing reinforced with 10-gauge plates. Larger Toro decks have 10-gauge shells with 7-gauge reinforcement plates," Guertin says. Decks also feature 2-inch-square tubular caster and lift arms. "The cutting unit is no longer viewed by the customer as something to be replaced several times during the life of the tractor," Guertin adds. "They are not a throw-away object, and we are designing them with that in mind."

According to Ferris' Dust, "All Ferris decks are manufactured with 10-gauge steel. Three key features separate us from others: lap-welded corners, a double-top deck welded together, and double-reinforced side skirts."

John Deere has introduced its stamped 7-Iron commercial deck. This is a 7-gauge, deep-dish, one-piece, formed-steel deck. "We think this will set a new standard for the industry. Most of our competitors use fabricated decks," says Breningmeyer. "The theory is that by fabricating, versus stamping, you have the ability to use thicker metals. Some will say you can't stamp a 7-gauge steel deck. The decks we are coming out with are indeed 7-gauge steel. Stamped decks are stronger than fabricated decks because they do not have weld points," Breningmeyer says. "Stamped decks also give a manufacturer flexibility in deck design. Deere's deep-dish design provides better air flow, which, in turn, allows operators to handle a higher volume of grass at a higher speed with good dispersal and cut quality."

The 7-Iron commercial deck now comes in a 60-inch size on the zero-turn models. This fall, the 48- and 54-inch decks will be available. The 60-inch 7-Iron soon will be available on a diesel rear-wheel-steer F735 mower.

Likewise, ExMark Mfg. Co. (Beatrice, Neb.) has improved the airflow capabilities of its decks. In model year 1999, the ExMark Lazer Z offers its UltraCut deck as a standard feature for its 60- and 72-inch models. The UltraCut is a deeper deck with enhanced airflow baffles to better circulate clippings.

Until this year, Snapper's largest deck was 61 inches. In 1998, it introduced a 73-inch deck for their out-front models. Snapper has 7-gauge-steel bent-and-welded decks. "Typical decks in this industry have been made of 10- and 12-gauge steel. We went to 7-gauge to make the deck thicker for more durability," says Lowe.

Magic Circle Corp. (Coatesville, Ind.) manufactures the Dixie Chopper decks with removable sections. "This allows you to drive the machine through gates as narrow as 36 inches," according to advertising manager Mark Meagher. "All Dixie Chopper decks are made of 7- or 10-gauge, formed, welded and reinforced steel. In fact, we reinforce the top of the decks with a 3/16-inch steel plate to help ensure an even cut," he adds.

Dixon Industries offers grounds managers a choice of 13-gauge- and 10-gauge-steel stamped decks or 13-gauge fabricated decks on its ZTR5022. The ZTR6025 has a 12-gauge-steel fabricated deck with 12-gauge reinforcements.

Similarly, Ransomes' Front Line 700 Series decks incorporate welded, 11-gauge steel with 7-gauge side skirts. Scagg features a 10-gauge-steel top with a 7-gauge support plate for added strength on its zero-turn-radius Sabre Tooth Tiger.

Mowers made by Encore Manufacturing Co. (Beatrice, Neb.) are equipped with welded-construction decks, which feature a channel on top, making them 5/16-inch thick, according to founder and President, Dick Tegtmeier. "This channel ensures the unit is mowing within 1/8-inch from tip-to-tip of the blade for a level cut. It also prevents the "oil-can effect" in heat zones and buffers vibrations," Tegtmeier says. Encore also features a 7-gauge top plate and 10-gauge side skirts.

The Upper Cut deck by Hustler is a free-floating rear-discharge mulching deck that stacks an additional set of small blades over the standard blades. "The Upper Cut deck has three blades, but also has a chamber that sits on top of those three blades where an additional set of blades re-cuts the clippings and discharges them out the back," Alfaro says. He notes that these finely chopped clippings readily sift into the turf.

Flip-up decks are popular for serviceability. They allow you to tilt the deck 90-degrees for access to blades or for storage. Several manufacturers, including Walker, Encore, Dixon, Snapper, Grasshopper, Deere, Toro and Howard Price Turf Equipment (Chesterfield, Mo.), feature flip-up decks on their out-front mowers.

Engines: sheer power Horsepower is the measure by which you compare engines, and you have a variety of engine options on rotary riders. Most engines are either gasoline or diesel. Of the gasoline engines, you can choose between air- and liquid-cooled models.

The liquid-cooled concept is similar to that of an automobile. Liquid cooling substantially extends the life of an engine. In fact, Encore's Tegtmeier believes an engine's life is extended to about 5,000 operating hours by liquid cooling. Snapper's Lowe agrees, "Liquid-cooled engines are becoming more popular because they will run a lot longer than an air-cooled engine." Breningmeyer agrees, "The market in the zero-turn-radius segment is beginning to move away from air-cooled engines and toward diesel and liquid-cooled engines."

For its air-cooled engines on zero-turn mowers, Deere uses a combination of Kohler and Kawasaki engines. For its heavy-duty rear-wheel-steer out-front mowers, Deere primarily uses Yanmar diesel engines.

Encore's zero-turn-radius mowers have engines that range from a 16-hp Vanguard V-Twin on its 42-inch models, up to a 22-hp water-cooled Kawasaki engine on the 61-inch-deck mowers. The company plans to offer an optional 26-hp diesel or a 30-hp liquid-cooled gas engine for its 72-inch-deck mowers.

The Dixon ZTR 5022 features 22-hp Kohler V-Twin Command engines. "Commercial operators like Kohler engines," says Kadel. "I think if you look around, you will find that the majority of the U.S.-made mowers have a Kohler engine. And the trend is to have them faster and bigger."

Most of Snapper's out-front and mid-mount commercial riders feature Kohler Command air-cooled engines, ranging from 22 hp to 25 hp. Snapper also makes models with 3-cylinder liquid-cooled Kubota gas and diesel engines, with 21-hp diesel and 23-hp gasoline models.

All Ferris mowers utilize air-cooled engines.

Walker Manufacturing has a range of Kohler air-cooled engines starting with the 16-hp OHC, the 20-hp V-Twin and the 25-hp V-Twin. The company also installs a liquid-cooled 20.9-hp diesel Kubota and a liquid-cooled 24-hp gas Kubota. Walker ensures its engines run clean and cool with a 3-stage air-filtration system. This includes a remote air-intake filter, a pre-cleaner (which has an internal fan with a paper element) and the engine air filter with a foam and paper element.

In 1998, Magic Circle Corp. began manufacturing the Dixie Chopper with liquid-cooled Yanmar diesel engines (available in 26 and 50 hp), according to Meagher. Dixie Choppers also are available with air-cooled Kohler engines with 20-, 22- or 25-hp options.

Toro's two-wheel-drive and four-wheel-drive rotaries use both gasoline and diesel liquid-cooled engines. "We use different engine manufacturers for a given application and for the given size of the equipment. Then we determine what type of an engine layout might help us drive the components," Koch says.

For instance, Toro's Groundsmaster 3000 series features 45-hp Ford VSG-411, 4-cylinder, 4-cycle overhead-valve gas engines and 33-hp Peugeot TUD5, 4-cylinder, 4-cycle, in-line, overhead-cam diesel engines.

In its 14 different models, Howard Price Turf Equipment uses Yanmar and Cummins diesel engines and Kohler and Kawasaki gas engines, according to president Howard Price. "People love horsepower. In different units, we offer different horsepower, and the higher horsepower out-sells the lower horsepower about three to one," he says.

Serviceability innovations Because of similarities in design, your buying decision may rest upon an intangible feature: the warranty of the machine. You should not be satisfied with anything less than a (minimum) comprehensive front-to-rear parts and labor (excluding blades, belts and tires) 2-year warranty.

Manufacturers' serviceability innovations address better ways to get at the engine, plugs, belts, hoses and other components. Various manufacturers provide field-serviceable blade spindles as well as no-tool in-field-belt-replacement capabilities. In addition, numerous manufacturers feature mower decks and hoods that flip up for easy access. The most important serviceability issue most manufacturers noted is how the components, as individual parts, hold up.

Michelle Byrne Walsh is a freelance writer in Island Lake, Ill. Specializing in grounds-maintenance topics.

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