Toro 03672, 03673, 03670, 03687, 03689 Articles

...

Greg Janey

Marketing Manager, Reelmaster Products

The Toro Company

Aftercut appearance, Part One: The science behind the art...

As most of you can attest, the one

thing you can always count on

changing is the environment — and

turf conditions along with it. At some

point in every turf manager’s career,

they will encounter turf and/or soil

variations that alter the aftercut ap-

pearance of their reel mowers.

After reviewing some of the latest

TurfNet Forum discussions regarding

aftercut appearance (ACA) on fairways,

we at Toro felt it appropriate to shed

some light on how the reel interacts

with the turf and how changes in turf

conditions can alter that interaction, as

well as share a few adjustment tips to

compensate for changing conditions.

Rather than provide a step-by-step

diagnosis tool, we want to help you bet-

ter understand how variations across

the season affect ACA, and in turn help

you better achieve the ACA you desire.

Our recommendations result from thou-

sands of hours of field testing and years

of research and development that cul-

minated with our Reelmaster 5010

series.

Every golf course (and even individ-

ual fairways) has its own unique condi-

tions that often require special atten-

tion. These variations can include differ-

ences in turf and soil composition, culti-

vars, seasonal growing periods, geo-

graphic location, water, fertilizer, and

even individual micro-environments

within a single fairway.

As a manufacturer, we design reel

mowers to perform optimally across a

broad range of mowing conditions. We

also provide a series of targeted adjust-

ments to compensate for turf variability

when conditions fall outside the range

of ‘normal’.

TurfNet Monthly, May 2008

Toro machines are shipped with

factory settings intended for the best

performance under the widest range of

conditions. They may, however, need to

be adjusted seasonally as dictated by

changes in specific turf conditions.

The following guidance is intended

to highlight ACA issues which can sur-

face during seasonal/environmental

changes, and provide directional adjust-

ments to compensate for them.

Changes in turf “spring rate” causing bobbing...

Varying levels of turf unevenness cause

fairway cutting units to hop vertically as

they traverse the contours in the fair-

way. Firm turf and heavier cutting unit

weight help stabilize the reels to mini-

mize bobbing and the resulting uneven

cut.

There is, however, a window in early

spring when the turf comes out of dor-

mancy, the soil is very soft, and the

“spring rate” of the turf approaches the

level needed to create bobbing of the

cutting unit.

distance the turf deflects under the

weight of the cutting unit. The softer a

turf is — the lower the spring rate — the

longer it takes for the cutting unit to re-

stabilize and stop bouncing.

This turf condition is not isolated to

the beginning of the growth season —

but that is when it most often appears.

To understand this further, think of

a typical spring suspension on a car as

it rides over a bump. If the suspension is

stiff like a sports car (a high spring

rate), the tire (or in our case, the roller)

will traverse through the bump and

quickly stabilize back to following the

contours of the road.

Spring rate

determines the

On the other end of the spectrum, if

the suspension is softer (lower spring

rate) like a Cadillac, the tire will traverse

through the bump, absorb some of the

energy, and continue to bob or sway

vertically long after the initial impact.

This is how the cutting unit can become

“excited” to the point where bobbing

occurs and continues across a fairway.

Soft turf with a low spring rate does not re-

stabilize cutting units as quickly as firm

turf does, so bobbing is more likely.

To offset this variation in turf, Toro

engineered a turf compensation spring

to optimize front-to-rear weight bias of

the cutting unit. This adjustment gives

you the ability to aggressively follow un-

dulations of a fairway during normal

mowing conditions, and if needed, shift

more of the cutting unit weight to the

rear roller to reduce any bobbing that

may occur during the growing season.

Under soft conditions, the turf compensation

springs may need to be adjusted to shift

more c/u weight to the rear roller.

Aftercut appearance (Continued from pg 12)

Wet Conditions...

Wet or spongy conditions create many

challenges for reel mowers. Cutting

units are designed to achieve a specific

mow height in relation to the bottom of

the rollers. Notice that I did not simply

say, “to achieve a specific height of cut.”

This is because the actual “effective”

height of cut (HOC) is influenced by how

far the rollers sink or engage into the

turf canopy.

The amount of engagement is de-

pendent on many factors, including cut-

ting unit total weight on the turf, sus-

pension system down-pressure, front-to-

rear roller weight bias, roller type

(smooth, grooved), canopy thickness,

amount of clippings, and even the

amount of grass/turf removed.

Under wet turf conditions, reel-to-reel setup consistency across the machine becomes more critical...

The effective vs bench-set HOC

variation becomes more apparent when

the turf is soft, as it will allow the cutting

unit to sink or engage further into the

canopy, resulting in a lower effective

HOC when compared to the same fair-

way when it is dry or firm.

Under wet turf conditions, reel-to-

reel setup consistency across the ma-

chine becomes more critical to ensure

a uniform ACA. Issues that may occur if

reels are not set up consistently include

scalping, marking, step-cut and excess

clippings, among many others. To com-

pensate, most reel mowers have vari-

ous roller options, adjustable counter

balance springs, and most importantly

HOC adjustment to allow you to achieve

the same effective HOC in a variety of

conditions.

When selecting a cutting unit con-

figuration, one must understand that

each cutting unit design or configura-

tion will have a different effective HOC

due to the differences in ground pres-

sure at the roller, the cutting unit sus-

Wet or high-growth conditions may require special adjustment to ensure a uniform

aftercut appearance across the full swath of the machine.

pension, the aggressiveness of cut, etc.

This means that the same HOC for one

type of reel mower will not necessarily

give the same result on another.

To ensure your mower provides the

desired ACA in wet conditions, it is most

important to ensure all adjustments

and attachments are set the same. If

needed, it may help to switch to full roll-

ers, add rear roller brushes, or in-

crease the HOC setting.

High growth conditions... (cutting unit overlap)

In times of high growth rates (like in the

spring, after fertilizer applications, or

even from extended periods between

mowing), the thicker canopy and in-

creased amount of leaf blade removal

create a unique mowing surface which

may alter ACA from reel to reel.

As the cutting unit rides over the

turf, the canopy acts as a support,

pushing up on the rollers and bedknife

with varying force depending on the

amount of turf or canopy thickness be-

low it. This is also part of the reason

why you observe a difference between

bench set and effective HOC.

Now, let’s address the fact that all

cutting units have a certain amount of

overlap between them to minimize un-

cut turf when turning or mowing on side

hills. The Reelmaster 5010 series with

22” DPA cutting units, for instance, was

designed with 2½ ” of overlap on each

side of the cutting unit. This means the

front three reels are exposed to a full

22” of thick, uncut turf canopy, while the

rear two only see 17” of full turf canopy

(and 5” of pre-cut turf). This is over 20%

less full canopy pushing up on the roll-

ers and bedknife, which in high growth

(Continued on next page)

Because rear cutting units are cutting (and being supported by) over 20% less turf than the front

cutting units, a counter balance

spring has been designed to

relieve some of the weight off the

rear cutting units — so they don’t

engage as far into the turf canopy.

(Continued on page 14)

TurfNet Monthly, May 2008

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