Reducing repetitive motion injuries during grape harvest is an
increasingly high priority in the grape industry. Robert Mondavi
Winery (Napa, CA) has taken a lead role in that effort by developing
a machine that helps grape pickers in high-density vineyards avoid
Robert Mondavi Winery has used a Box Retrieval System (BRS) for
the past three harvests in selected blocks of its Napa Valley
vineyards (vines spaced 4-ft x 4-ft). The system spares workers
the traditional burden of lifting and carrying grape-laden boxes
weighing 40 to 50 pounds as many as 40 times each day.
Michael Christensen, Mondavi technical operations manager, reports
that while the BRS system is still too new to yield hard data,
early anecdotal reports from the field are encouraging. The system
seems to be reducing repetitive motion injuries.
The idea for the Box Retrieval System was spawned in 1999
during discussions between our staff and Mathews Mechanical in
Newark, CA, says Christensen. We were looking for
a mechanical way to lift and carry the boxes to reduce the incidence
of back injuries.
In Napa Valley, where grapes are mostly handpicked, rising workers
compensation premiums are a serious concern. Employers are looking
for every possible means to lower their premiums, which are influenced
by the number of employee injury claims.
Dr. John Miles, professor in Biological and Agricultural Engineering
at the University of California, Davis, reports that most injuries
in vineyards are caused by lifting and carrying.
At the UC Agricultural Ergonomics Research Center, Miles and his
colleagues have been studying the effects on workers of repeatedly
lifting heavy boxes of grapes and carrying them to the end of
a vine row, where they either stack boxes on a trailer or dump
them overhead into a large gondola. Mondavi began consulting with
the UC ag research group early on in its plans to develop the
High-density vineyard implement
The BRS fits on a French-made Bobard 896 over-the-row tractor.
The Bobard was purchased for Mondavis high-density vineyards,
where there is not enough room to run even the smallest conventional
tractor down the four-foot wide tractor rows. The Bobard can operate
in tractor rows as narrow as 40 inches wide. Mondavi has more
high-density acreage planted than any other winery in California.
We didnt buy the Bobard tractor for harvest,
says Christensen. It was an existing machine in our fleet
and is a common tractor in France for high-density vineyards.
We use the Bobard tractor for spraying, cultivation, and vine
trimming throughout the year, then we attach the BRS for the harvest
Christensen is also hopeful that the BRS will apply to conventional
(six feet and wider) rows. Mitchell Klug, director of the Napa
Valley operations for Mondavi, believes it will. After we
did the ergonomic studies and decided to go forward, Michael seized
the idea and tackled high-density vineyards first, where injuries
were higher, Klug notes.
How it works
The BRS equipment is 26 feet long and 10 feet at its broadest
width. It consists of three conveyors, a hydraulically actuated
box ejector mechanism, a roller table, and a work platform. Conveyors
are powered using the tractors auxiliary hydraulic power.
The work platform can accommodate two workers and two full pallets
of fruit (approximately two tons) or two half-ton bins and two
During harvest, workers on the Bobard tractor distribute empty
boxes to every other tractor row. When boxes are full, pickers
leave them in the middle of the tractor row. Arms on the BRS guide
each box onto the lift conveyer. The lift or incline conveyor
delivers boxes up to the roller conveyor at the rear of the machine.
After each box ascends the incline conveyor, the hydraulic ejector
is actuated, and the box is automatically transferred to a roller
table, which has a slight decline.
Each box is hydraulically propelled down the roller table toward
the front of the machine at chest height. A worker removes the
box and stacks it on a pallet or empties it into the larger bin.
Full pallets or half-ton bins are then off-loaded on the vineyard
headland and moved to a staging area via conventional vineyard
tractor and trailer, while the Bobard returns to the picking area.
During the first couple of off-seasons, the BRS was returned to
fabricator Mathews Mechanical for fine-tuning. Owner Jeff Mathews,
whose company specializes in custom material handling, says the
latest modification was the addition of an elevator that lowers
empty boxes to the ground. Before, if the worker on the
platform emptied boxes into the half-ton bin, he would have to
find somewhere to put them. The elevator takes care of that problem.
Grape picking crews in Mondavis To Kalon and Huichica Hills
vineyards, where the BRS is used, dont exclusively work
with the machine. Instead, they move between machine-assisted
blocks and vineyards with larger spacing where they must carry
loaded boxes to the ends of rows or to tractors. Its no
surprise, Christensen reports, that workers say they feel better
and that the job is easier for them when they work with the BRS.
UCDs Grapemover prototype
In the Ag Ergonomics Research Centers vineyard injury study,
the UCD staff took a two-step approach. We wanted to eliminate
most of the lifting and carrying activities, says Miles.
We collected considerable data that showed we could reduce
the persistent pain among the workers by 50% just by reducing
the weight of boxes from 57 to 46 pounds. In the next step,
they created a machine similar in concept to Mondavis BRS,
but designed for wide tractor rows rather than high-density vineyards.
The Grapemover was tested in a prototype in 2001 and
with a production run in 2002.
Our data from 2002 is being studied but is not quite ready
for release yet, reports Miles. However, he expects that,
through the use of the Grapemover, new injuries will be reduced
to almost none.
We have not completed the data analysis, but I believe the
number of people reporting persistent pain is going to be a small
number. It will not be zero, because the data show that something
between 10% and 20% of the workers report persistent pain before
the season starts. I think our data for picking the grapes, but
only doing very limited lifting and carrying, will show similar
numbers [to the pre-harvest reports of pain] at the end of the
The BRS has cost Robert Mondavi Winery about $50,000 to develop,
manufacture, and modify. We know were on the right
track, explains Christensen, But at this point, the
benefits just havent been documented.
One reason is that only 15% of the harvest in the high-density
blocks is carried out utilizing the BRS. It would require
multiple machines to take care of all the 4x4 spaced vineyards,
Christensen adds. We have only one and it is still being
In addition, expenses are approximately $50 higher per ton in
vineyards using the BRS. But this minimal added expense is offset
by a number of other considerations, Christensen suggests. Among
them is the winerys broad view of what encompasses good
We have a lot of long-term workers, many of whom work year-round,
notes Christensen. We are always looking for ways to mechanize
and take the burden off them. We believe this machine is one of
those ways. We just have to make it more efficient and economical.
Klug believes the BRS is successful in helping to mitigate the
physicality of the harvest. This machine allows pickers
to make harvest decisions, pick the fruit, pull boxes into the
center of the row and walk away. That is clearly better for them
than carrying the boxes and lifting them over their heads and
dumping them into containers.
This kind of machine may well allow people to pick for a
longer period of time in their lives. Right now you need a strong
person. With the BRS, vineyards could potentially expand the pool
of people they can use. Were a sustainable winery. Being
sustainable means maximizing potential earnings and employee safety.