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How your tunnel controller works

October 11, 2010
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Whether you know it or not, your occipital cortex, frontal lobe and temporal lobe are all firing away as you read this sentence. They are the parts of your brain that enable you to read.

Most operators are equally unaware of the job the tunnel controller performs as soap sprays, mitters flop and dryer blades spin. While a good tunnel controller doesn’t require much operator interaction, understanding how it works can save hours of trouble-shooting time when something goes wrong.

The carwash body
The comparison of the tunnel controller is fitting when you look at the carwash as a body. The cloth and mitters are the hands that reach out and touch the vehicle. They’re controlled by the motors, which act as muscles. The muscles get life from the hydraulic power packs and electrical generators that pump life into them. This motion is a result of reactions from the entrance switch, pulse switch and other sensors that act as the eyes and ears of the tunnel.

At the very center of all of this activity is the tunnel controller — the all-important “brain” of your tunnel. Shut the brain down and the rest of the body stops.

Just as the human brain has different parts, so does the tunnel controller. The tunnel controller can be broken down into four parts:

  1. The computer;
  2. The user interface;
  3. The relay outputs; and
  4. The push button box.

Basic operation
After you first install the tunnel controller, settings are controlled via the user interface. These settings are stored on the main controller.

When a vehicle arrives at the tunnel, an order is entered on the push button box. This order is transmitted to the main controller so that the controller knows (based on the programmed settings) what relays will need to turn on for that particular vehicle.

Once the vehicle trips the entrance switch, the controller is alerted and begins the wash sequence. It knows when to turn each relay output (and therefore each piece of equipment) on and off based on the programmed settings as well as the speed of the pulse switch.

After each vehicle goes into the tunnel, a record of the transaction is added to the database so that you can view and print reports when needed.

The computer
All controllers built in the last 15 years have, at their core, some type of computer. I remember the first computerized tunnel controller model in the late-80’s, where purchasers received a sticker they could use at the wash. “This carwash is controlled by a computer.” Most operators would proudly display these stickers in prominent places so their customers would be impressed by the sophisticated technology installed in their carwash.

At the time, computers were not household items like they are now. Looking back, my current cell phone has more processing power than that controller.

Nowadays, people assume that computers are used everywhere and so no one is going to be impressed by your “computerized” carwash. However, it’s the computer that allows us to program settings without changing dozens of tiny dipswitches, print detailed reports and control equipment precisely.

The computer stores the software application that runs the wash as well as the database that contains settings and transactions. Some controllers have hard drives that store this information. Others have some type of memory chip such as flash memory or, removable media such as a compact flash card.

The user interface
The user interface allows the operator to interact with the controller to edit settings (i.e. turning on a piece of equipment, details of a sale, etc.), view and print reports. Some controllers have the user interface built directly on the controller via a small LCD screen with buttons. Some may use special software that loads on a standard PC. Others connect to the controller via a web browser in any standard PC. In this case you simply network the controller and the PC (an internet connection is not needed).

Most controllers will also give you the ability to access the user interface remotely from your home or office. This can be done via a modem or high-speed Internet connection. Some controllers also offer remote reporting via pagers, cell phone text messaging and/or email.

It is vitally important for an operator and manager to have a good understanding of how to access the user interface and software navigation. Any operator or manager should easily be able to change turn on/off times for a piece of equipment, change wash packages, edit prices and basic information like date, time and sales tax. It is recommended that a manual for your user interface is easily accessible and also that you have a hard copy of all your settings.

The relay outputs
The low voltage relay output is what connects to the actual equipment in the tunnel. This could be connected to an air or fluid solenoid valve, to a motor starter (which is then connected to the motor) or to a tunnel sign.

Each controller manufacturer has proprietary relay output circuit boards. Some have four relay outputs per board, others have eight, 16 or 24. Basically the more relays per board, the cheaper the cost is per relay. However, a relay board with fewer relays makes it easier to purchase the amount of relays desired.

There are different kinds of relays that can be used. Some controller manufacturers use single pole relays, which require you to connect a 24V signal to a 24V relay and a 120V signal to a 120V relay. In this case, a relay output has to be either one voltage or another.

Other controller manufacturers use double-pole relays that allow one physical relay to have two voltages (i.e. 24V and 120V). In this case you would simply connect the equipment to the necessary terminal blocks for that voltage. With a double-pole relay you could turn on a 24V soap solenoid valve and a 120V wrap motor with the same physical relay. This has the advantage of using fewer relays and therefore lowering the price of the tunnel controller you need.

Most relay output circuit boards have toggle switches with an on, off and auto position. This allows an operator to manually turn a piece of equipment on (to test), off (i.e. if a soap line is leaking) and auto (if everything is working fine and you want the controller to be able to turn the relay on and off at will).

The push button box
This is where the orders are placed and sent to the controller. They come in different sizes and number of buttons. They are designed to endure the rigors of the employees and the environment.

This is probably the most likely piece of equipment to wear because of the environment. Most manufacturers could easily make them more rugged but this would cause a significant increase in price, making a single push button box five to ten times more expensive than current models.

Most controllers will allow you to make a particular button a wash package (i.e. bronze wash, silver wash, gold wash, etc.), an extra service (i.e. triple coat wax, armor all, etc.) or an override (i.e. vacuum on/off, prep gun on/off, tire retract, etc.). These are programmed through the user interface.

Most push button boxes also allow you to connect a receipt printer. Some print bar codes that can be read by a integrated point-of-sale software system so that the order does not have to be re-entered by the cashier.

Some controllers will allow you to have multiple push button stations. This requires that the controller be capable of random stacking, which means that the vehicles can be entered into the tunnel in a different order than in which they were programmed.

For example, let’s say you have two push button boxes that you are selling from. The vehicle in the left lane gets entered first and orders a basic wash (we’ll call him order #21). Next an order is entered for the vehicle in the right lane and he orders the top of the line package (order #22). However, let’s say that order #2 is ready to enter the tunnel first.

At this point the controller needs to know which vehicle is entering the tunnel so that it knows which extra service outputs need to be turned on. Therefore a third push button box is mounted at the entrance of the tunnel. Instead of having the same buttons as the others, this has the numbers zero through nine. When the vehicle enters the tunnel, an attendant enters the order number of that vehicle. According to our scenario above the attendant would enter 22 and then hit the enter button. The controller would then know that this is order #22, which is the vehicle getting the top of the line wash.

Some controllers have this ability built in and others require you to purchase additional hardware and/or software.

The more you know about your tunnel controller, the more time and money you will save over the long run.


Kyle Doyle is a former carwash operator and current owner and CEO of Compuwash, Inc., a 27 year-old, NY-based manufacturer of tunnel controllers and point-of-sale software. He can be contacted at kdoyle@compuwash.com.

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