Greenhouse Mechanization and Material Handling
Plant Handling Systems
Reducing plant handling costs is a goal of most greenhouse businesses. Moving plant material is time consuming, heavy work, and expensive in terms of labor costs. There are many plant handling systems that can be used to reduce this task and its cost. The following are some typical plant handling systems used in greenhouses to improve productivity and efficiency.
Conveyors
Moving materials is one of the most labor-intensive jobs in the production of plants. Although carts are becoming more popular as a method of moving container plants, conveyors are more versatile in that it can quickly move cartons, bags, bales, bulk soil as well as plants. Conveyors are available in any width or length needed. They can be installed permanently or set up temporarily. The conveyors are installed inline so that product can be moved from one conveyor segment to the next. A conveyor should be “capacity matched” to the input rate of your materials flow. If it isn't, it may cause a bottleneck, limiting the efficiency of your system. It also has to be installed and maintained properly. Many types of conveyors are used in greenhouse operations including belt, gravity, chain, auger, overhead monorail, and.
Belt Conveyors
A belt conveyor works well for moving boxes, bags, bales, pots, flats and bulk materials (See Figure 3.8). It may have legs or may be designed to be placed directly on the floor. If the conveyor is to be moved frequently, a carriage with pneumatic tires and a winch will make the job easier. Most manufacturers have several styles, including trough, flight, and flat belt conveyors. For most horticultural uses, a light- to medium-duty unit will provide good service and is available in widths from 4 to 24 inches and lengths to 200 feet. A lightweight, self-contained unit with an enclosed bottom works well for loading a truck or moving a shipment of containers into an elevated storage area. These units will support 300 to 400 pounds easily and are powered by an electric motor.
Gravity Conveyors
Gravity conveyors are ideal for moving boxes, bales, and flats, either by manually by workers pushing the material down the line or by allowing the maerial to move by gravity (See Figure 3.9). Because of the bumpy ride the rollers create, this conveyor is better suited for products with long, flat bottoms, such as flats of boxes, rather than individual pots. There are two basic types of gravity conveyors: wheel and roller. The rolling surface of a wheel conveyor is a series of small-diameter skate wheels supported by a metal frame. Light loads and items with solid bottoms work best on this conveyor.
Chain Conveyors
Chain conveyors are used for moving of materials horizontally or between floors (See Figure 3.10). They are also used in potting machines and bale breakers to move the soil vertically. The simplest system uses a single endless chain to carry pots from a potting machine to carts or trailers for transferring to the growing area. Motorized conveyors are available, but these are more expensive.
Auger Conveyors
Auger conveyors are used to convey or elevate granular materials, such as growing mixes, peat, vermiculite, sawdust, or chips (See Figure 3.11). Augers are preferred for these applications to other types of conveyors because of their simplicity, low cost, durability, and versatility
Gantry Conveyors
Gantry conveyors are common in gutter-connected greenhouses (Figure 4.8). A gantry is a beam or frame, with wheels on both ends, that is supported on rails. It spans over a bay of plants and is pushed by hand. The rails, usually pipe or angle iron, are attached to the sidewall posts and extend the length of the bay. Frequently, pipe rails also are the heat pipes. A gantry can be built with one or multiple shelves to carry the plants.
Overhead Monorail Conveyors
An overhead monorail conveyor can be used to eliminate the time-consuming and backbreaking job of moving plants from the transplanting area to the growing area and on to the shipping area (See Figure 3.12). This system consists of tubular or angle iron track suspended from the greenhouse frame and a trolley-mounted rack that is pushed along manually.
Carts
All sizes of greenhouse operations can benefit from carts (See Figure 3.14). They increase labor efficiency by allowing one person to move more material at one time than could be carried by hand. Most carts have variable shelf spacing to handle different sized plants and containers. Typically, a cart for moving bedding plants will hold 25 to 30 flats.
Forklifts
Forklifts or lift trucks are efficient in moving mate rial, but their main purpose is for lifting and stacking (See Figure 3.15). Ubiquitous in warehousing operations, forklifts are commonly used in greenhouses, as warehousing or similar operations often occur here to some degree to receive, store, and distribute the supplies needed for plant production, harvesting, and transport. Most greenhouses use some degree of palletization.
Front-End Loaders
Front-end, or bucket, loaders come in three basic types: skid-steer, wheel, and articulated-body loaders (See Figure 2.13). The skid-steer loaders tend to be smaller but are used to take advantage of their size. The skid-steer method of turning enables the vehicle to turn within its own length, an advantage in tight spaces. They can also be used for other tasks.
Tractors, Trailers, and Other Vehicles
Although many more methods are possible for moving plants in a greenhouse, the tractorand-trailer method is a widely used one. Farm tractors a recommonly preferred as the motorized unit because they are widel y available, but many other types of vehicles are used to pull trailers.
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