Picture this: Your dishroom employee comes in late, and the backlog of trays from the lunch rush has made a mess of both the dishroom and soiled tray drop-off in the cafeteria.
Or how about this? The tray of your first cafeteria customer of the day hit the limit switch at the end of your straight-line conveyor from cafeteria to dishroom, shutting it off. Now, all your lunch patrons are stacking trays in the drop-off window, making a huge mess.
If scenarios like these sound familiar, a potential solution for your operation is a carousel-type soiled tray accumulator. This style of tray accumulator is pretty self-descriptive—racks that accommodate soiled trays revolve on a carousel-like device. Simple, really.
What’s the big deal? Well, say you have 20′ length of flat conveyor that carry trays from your cafeteria back into the dishroom. You can fit about 13 or 14 trays on that length of conveyor. Unless you have an employee back there scrapping trays, the fourteenth or fifteenth customer in your cafeteria will have no place to put his or her soiled tray. And unless you have two employees in the dishroom—one to scrap and one to load soiled dishes in racks—the dishroom probably won’t be able to handle the incoming trays quickly enough.
A 9′-long tray accumulator, on the other hand, can accommodate anywhere from about 36 to 60 trays on multiple tiers at one time. That allows trays to accumulate until an employee can get to them, and usually means that one employee can handle incoming soiled trays during a rush because there are places for patrons to put them while the dishroom is catching up.
As you can see, tray accumulators are probably best suited to a cafeteria operation where patrons bus their own trays. In a patient feeding operation, trays can be left on carts until dishroom employees have time to break them down. An accumulator isn’t as necessary or as helpful.
There are a couple of other caveats if you think a carousel tray accumulator might be just the ticket in your operation. First, location is key. Patrons deposit soiled trays on one side of the carousel and dishroom employees remove them on the other. Obviously, the cafeteria has to share a wall with the dishroom.
Space is something else you have to consider. A typical carousel unit is about 52″ wide versus about a third of that for a flat conveyor. A couple of manufacturers now make compact over/under models that rotates like a Ferris wheel instead of a carousel, taking up about half the width of a conventional accumulator.
What’s Your Style?
Carousel tray accumulators operate in a couple of different ways. All basically accomplish the same job, but there are subtle differences, and you may have a preference for one over another.
Most manufacturers make carousels that operate a little like a chairlift at a ski resort, but with chairs facing out from the center rotator. Tray racks hang on a chain that rotates around the top of a center oval. Wheels at the bottom rear of the racks either roll in a track or against a slide on the center unit to stabilize them.
One manufacturer builds its carousel without a raised center, instead locating the drive chain at table height. Its racks are three-sided (U-shaped) carriers with tray slides inside that roll on wheels in a track around the stainless oval table. The carriers are hooked together like train cars, and pins on each carrier come in contact with the drive chain, which pulls them around the oval table.
Finally, another manufacturer makes a slightly different variation on theme. Like the style above, this manufacturer makes three-sided wire racks on wheels, but instead of being pulled by a drive chain, the racks ride on a conveyor belt. There are a couple of potential benefits to this format we’ll mention a bit later.
Operation is pretty simple. An on/off switch and in some cases variable speed control are the only controls on these units. Variable speed gives you the flexibility to adjust throughput depending on how many people are in the dishroom to scrap trays and load dishes in the warewasher. Speeds range from about 10′ to 25′ per minute, usually not fast enough to cause trays to shift even when they accelerate around the corners. (The conveyor belt style accumulator avoids this problem altogether; like the conveyors in airport baggage claims, it’s designed so it doesn’t accelerate on corners.)
Virtually all tray accumulators come with a safety switch that shuts off the drive mechanism if a tray isn’t pushed far enough into the rack and sticks out enough that it could hit a wall and jam the equipment.
In some cases the safety feature is a mechanical proximity switch; in most it’s an optical beam. A potential problem with the optical beam (more on college campuses than elsewhere) is that mischievous guests can interrupt the beam with their hands or some other object and stop the machine.
The conveyor belt carousel doesn’t require a safety switch. Because the tray rack carts float freely on the belt, if a tray isn’t properly seated and catches on something, the cart stops (and stops all the carts behind it), even though the conveyor belt continues to move under the carts.
When an improperly seated tray does stop an accumulator from revolving, usually an employee must come out to the dining area and push the tray all the way into the rack. However, an option on at least one manufacturer’s units is an automatic tray repositioning bar. If an improperly seated tray triggers a sensor, a bar swings out and pushes the tray into the rack before it can cause a jam.
Racking Up Capacity
Most basic tray accumulator models are oval shaped, and manufacturers make a wide variety of standard sizes from 9′ long to 36′ or more. They also can customize other shapes such as triangles, rectangles and even serpentine or “L” shapes. That kind of design flexibility helps if you have an oddly shaped dishroom, or are squeezed for space.
Racks are designed to hold from two to five trays. Typically, you’ll find a lot of three- and four-tiered models on the market. In general, the more trays you can accommodate on an accumulator the better, but a number of factors come into play when making your choice.
One is physical space. The layout and size of the space you have for an accumulator may affect the number of tray tiers you’ll be able to accommodate. Low ceilings, for example, may preclude you from using a four- or five-tier model.
The height of your glassware also is a determining factor. Obviously the tiers on the tray racks have to be spaced far enough apart to allow trays with glassware and tableware to fit on top of each other. The taller your glassware, the fewer tiers your unit will have.
Even the audience you serve may play a role in the capacity of the model you select. A tray accumulator in a nursing home dining room, for example, may have to be accessible to mostly wheelchair-bound patrons.
As mentioned earlier, racks on the chair lift-type of carousel typically are wire. The racks and carriers usually can be removed for easier cleaning. In most cases they break down so you can run them through your dishmachine. Some manufacturers of the chair lift-type also offer enclosed or three-sided racks as an option.
The other types of carousels use three-sided carriers with wire tray slides inside. These, too, can be taken off the accumulator for cleaning, but may or may not fit in your dishmachine. If not, employees would have to hose them down or wash them manually from time to time. Since most designs for tray accumulators include hoses for scrapping on the dishroom side of the carousel, this usually isn’t a problem.
You can order racks that accept trays end-on or side-on. End-loading accumulators have greater capacity than side-loading machines of the same length. But remember, end-loaders will be wider, so make sure you have space in your dishroom before you specify which type you want.
You may be asking yourself what happens if a guest doesn’t use a tray or you have a trayless operation. At least one manufacturer offers a solid bottom shelf as standard equipment on its racks, but all offer solid shelves as an option on one or all tiers of their racks. Some offer theirs in ABS plastic, others in stainless steel. Obviously stainless is more expensive, but it tends to be more durable, too.
Driving Construction
These units are typically built to last, but construction details may make a difference to you when you set your specifications. Obviously, the more durable the materials, the longer the equipment is likely to last.
Stainless construction is pretty much a given, but some manufacturers use more of it in more places, so pay particular attention to spec sheets when sussing out how one is made versus another. Most manufacturers use steel chains, for example, since they’re typically at the top of the unit and out of the way of spray hoses in the scrapping area. But a dishroom creates a moist environment, so one maker uses a stainless steel chain.
Gauge is important, too, since you want the equipment you buy to stand up to abuse and wear. Twelve gauge is better than 14 gauge, for example, and 11 gauge is sturdier than 12 gauge.
If you have the time and budget, visit your potential supplier’s factory and see how their units are made. If you don’t, at least ask. Some manufacturers, for example, build their accumulators on three separate platforms and weld these together. At least one manufacturer constructs the entire unit on one platform, an advantage being that it has fewer legs, making it easier to clean the floor under the unit.
The type of drive a unit uses also might affect its life cycle. Some models use direct drive, some use chain drive and yet another uses a V-belt. Direct drives are likely to be the most reliable, and belt drives the least reliable because the belt can loosen over time or even break. Belts are relatively inexpensive to replace, however, if price ends up being a deciding factor.
The chain on which tray racks hang also needs attention. The majority of units with plain steel chains, not stainless, will need occasional lubrication to keep them operating smoothly. Some models have a self-lubricating chain, so you don’t have to worry about making sure employees do it periodically.
Chains also may need adjustment from time to time, since repeated use can loosen them. At least one manufacturer has a self-adjusting chain. A spring-loaded device provides constant tension even if the chain starts to loosen due to wear. Otherwise, employees may have to manually adjust chain tension from time to time.
The key to trouble-free operation is a unit that runs as smoothly as possible. As mentioned earlier, the chair lift-type of carousels have wheels at the bottom to provide stability and reduce vibration and sway. They may fit in a track or sit against a slide strip. The strip, the wheels themselves, and even the chain guide track are typically made from a plastic material such as nylon, polyethylene or Delryn. The name isn’t as important as the fact that the material is some sort of ultra high molecular weight (UHMW) plastic, which doesn’t wear out quickly, is “self-lubricating” and offers the least amount of friction for smooth operation.
Design Considerations
Almost as important as the accumulator itself are the options and design considerations you need to make. Let’s start with aesthetics. Dishrooms are noisy places, so most manufacturers make baffles that fit over the top and near the sides of the tray accumulator to keep sound out. They also block cafeteria patrons’ view into the dishroom.
Baffles block out light, as well, which means that the dining area side of the carousel can be dark and uninviting. Some manufacturers offer different finishes on the riser in the center of the carousel besides just stainless. Some have powder coat colors. Others offer plastic laminate panels in a variety of colors. The manufacturer of the conveyor belt carousel uses backlit translucent panels in the center of its unit, providing patrons with more light in the soiled tray return area. And lights are an option on overhead baffles from some manufacturers.
From a practical standpoint, you may want to look into other options on the dining area side of the carousel. First is what sort of table to put under the revolving racks (if you choose a chair lift-type accumulator). Some facilities, particularly those in B&I and college/university operations, have chosen to leave the floor open under the racks for aesthetic purposes. Many operators choose to put a stainless table under the racks, sloped toward a center drain to catch any spills.
Manufacturers can provide other options for fabricators or installers such as garbage chutes, receptacles for composting and recyclables, and a flatware catcher.
On the dishroom side, you have an equal number of choices to make. Some of them will be influenced by the dishroom layout and whether you use a flight-type or rack warewasher.
As employees take trays off the accumulator, though, you’ll want at a minimum a table with a scrapping trough, and hoses for pre-rinsing dishes. But here again you can choose from options such as chutes for garbage as well as recyclable and compostable items, the addition of a disposer or pulper, a flatware soaking sink, and more. You also may choose gravity rollers or a conveyor belt to move racks of soiled dishes to the warewasher.
Keep It Moving
Not a lot of maintenance is required for tray accumulators other than what’s been mentioned already. Look for designs that offer easy access to the motor, the drive system (whether direct, chain or belt), and the chain (if a chair lift type). That way, your staff can easily lubricate parts when necessary, or adjust and tighten the chain and/or drive system.
Controls, too, should be easy to access, but out of the way of water spray or potential dishroom accidents. Some manufacturers also offer remote start/stop controls so employees don’t have to walk out to the dining area to fix a jam and walk all the way back into the dishroom before starting up the carousel again.
As you gather information from manufacturers on the accumulators they make, ask for names of operators in your area who use them so you can go on site visits and see how the units might work in your facility. Be sure to include employees in the dishroom and on your maintenance staff in the purchase decision-making process.
Finally, as you narrow your choices, be sure to ask manufacturers about warranties, service networks and technical support for any problems you may encounter down the road.
Tray Accumulator Suppliers
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