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Sunday, March 24, 2019

WSU-TFREC/Postharvest Information Network/Reducing Emissions from Forklifts

Reducing Emissions from Forklifts

Evolution of the Forklift

CLARK manufactured the first forklift in 1917, eighty years ago; it was powered by gasoline. Over one million forklifts later; we still power them with gasoline. But now in North America, the majority of forklifts are LPG powered. (In Europe the majority are diesel.)

Gasoline, diesel, and LPG will still be available in the near future, but the most research and development dollars are being spent on the fastest growing, most innovative, and cleanest trucks ever built. The trend, or evolution, is now heading toward the Electric Powered Forklift.


The spent gases of the internal combustion engine have always been a problem. Carbon monoxide (CO) and hydrocarbons (HC) are what we measure to gauge the efficiency of an engine.

Forklifts have served American industry well. Safety improvements have been constantly addressed (the latest being the Safety Wing, or hip restrains now found on all seats). Today all manufacturers are aggressively seeking ways of reducing emissions.

Currently there are many different engines offered in the various brands of manufacturers. Different engines of different designs cause great differences in the emissions that come out of the tail pipe. What would be considered good and clean to one engine, can be grossly out of tune for another. Older flat head designs with low compression ratios are impossible to get as clean as the newer overhead cam engine. This makes it impossible for us to state a "acceptable" or "good" emission percentage reading. This variance is what separates a mechanic, from a true technician. One needs to know how clean, or lean, an engine can get and still run properly.

Proper maintenance is critical to clean engine performance. Every 250 hours a forklift should be serviced and checked for proper emissions. This cannot be over emphasized as trucks that are running poorly are emitting very large quantities of emissions.

Our most frequent call out for excessive emissions relate to an out of tune, or neglected forklift. By simply practicing good maintenance we can eliminate excessive emissions. Also a prime candidate for excessive emissions is an older forklift. As an internal combustion engine ages, it will lose compression and start to burn oil. Both of these will increase emissions. Please don't spend large dollars to keep an aging forklift running. Retire it and start depreciating a new or newer lift. Fleet rotation is critical to proper fleet management. Heavy use, 2,000 hours annually, would require a suggested rotation of every five years. For example, if you have twenty trucks in your fleet, you should be replacing four trucks each year. This will minimize emissions throughout your facility.

Decreasing Emissions

The first step in decreasing the emissions in your forklift fleet is to get them all serviced and tuned. A gas analyzer will allow the technician to advise you of your worst polluters. It is then your responsibility to evoke the necessary repairs.

LPG trucks can be further cleaned up, and emissions reduced by the addition of a catalytic converter. While the older models were quite noisy, the latest models maintain the current low noise the standard muffler emits. A catalytic converter can be added to an existing LPG truck for about $600 to $800.

The next step in seeking fewer emissions for LPG forklifts is a computer-controlled closed loop carburation system coupled with a catalytic converter. This is where a computer monitors the oxygen in the exhaust manifold hundreds of times per minute and regulates the flow of fuel and air to optimize performance and minimize the emissions. These are currently used on all gasoline automobiles and have proven to be quite effective. They can be retrofitted onto existing trucks, and of course they can be ordered on new trucks. The system is expensive, (Approx. $2,000) and requires maintenance more frequently than a non-computer equipped truck. It is highly recommend if you insist on running LPG trucks inside. It should be noted that current laws in California prohibit the running of LPG powered trucks inside. It is inevitable that similar laws will be passed in Washington in the future. Keep this in mind prior to ordering up an entire fleet.

Compressed Natural Gas - The next step toward zero emission is to opt for a standard internal combustion truck that runs on CNG (Compressed Natural Gas). It is much cleaner than LPG (advertised as up to 80% cleaner than LPG), and offers the same truck operation as a LPG powered truck. The CNG is offered in a kit form or may be purchased direct from the factory on new trucks. While the CNG conversion is not too expensive, a filling station will be required to fill the trucks. CNG is currently plumbed into most areas at about 2 to 3 psi, and the truck will require 3,000 psi minimum to get good run times between fills. This means the fill station must pump holding tanks to 3,000 to 3,500 psi to allow quick fills. Depending on the size of your CNG fleet, a filling station can cost from several hundred dollars to tens of thousands of dollars. The advantage of CNG is that you get to keep the basic LPG style truck with the absolutely minimum emissions.

The only thing better than CNG available today is the electric powered forklift. It basically has zero emissions during operation. New batteries and chargers have greatly reduced the emissions while charging as well.

The Electric Difference

Gas or LPG powered trucks have greater initial acceleration than electric forklifts. They can spin the tires and sound like they are going FAST. In reality, the new electric trucks can generally have a higher top speed and are definitely faster in hydraulic operation. They are inherently more stable and thus allow more actual productivity than LPG in the right application.

Several major differences in the operation of the Electric trucks have caused some resistance in the switching from LPG to Electric.

The hydraulics is the biggest adjustment for an experienced LPG driver to adapt to in the operation of an electric truck. On a LPG truck, the hydraulic pump is driven off the engine by either gear or belt drive. Thus the hydraulic pump pressure, or output, is directly related to engine rpm. Your drivers are currently used to pulling the lift lever all the way back, fully opening the valve, and then revving up the engine to accelerate the forks to the desired height. On an electric truck this operating sequence would cause an abrupt jumping of the forks in an upward movement.

An electric truck is controlled by a controller; a computer. The computer senses the operator's inputs and acts or reacts accordingly. In the case of the pulled lift lever, the computer senses the initial movement of the lever and sends power, electricity, to the hydraulic motor. A DC motor that almost immediately turns the pump to full speed drives the hydraulic pump. This means that when your operator opens the valve, full pressure is applied to the fork immediately and the forks "jump" in their initial upward movement. The operator feels he has no control and subsequently dislikes the truck. The proper operation would be to slowly "feather" open the valve, controlling the flow of hydraulic pressure with the opening of the valve rather than the RPM of the engine. This allows far greater control and sensitivity, but it takes time to become proficient at this new method. Experienced drivers do not like to relearn their trade, and thus one of the hurdles to opt for electric trucks is born.

On a positive note, the annual maintenance of an electric truck is approximately 30% that of a similar LPG powered truck. Brake life will be two to three times that of a LPG truck, and tire life will be even greater. The electric truck will be much more comfortable for the operator than any LPG truck. There will be no vibration. The noise will be greatly reduced.

Caution: due to the extremely low noise of all electric trucks it is imperative that back-up alarms and strobe lights are installed to allow employees time to adjust to such quiet forklifts.

There is no inching brake so his/her left leg will have no duties to perform. There will be no "vacuum cleaner" effect, which is where the fan is blowing out through the radiator and out the back of the truck, causing suction under the bottom of the truck. This picks up any dust or dirt on the floor and disperses it in the air and into the eyes and noses of employees.

Batteries and Chargers

The current batteries used today are extremely powerful. Properly sized, they can power a full sized 5,000-lb capacity truck up to ten hours without recharging, or installing a fresh battery. Please keep in mind that the drive motor does not draw as much power as does the hydraulic pump. Long runs and travel distances do not drain a battery nearly as fast as hydraulic operations such as dumpers or push-pulls (i.e., slip sheeters). This means that unless you run two shifts, you can probably get by with just one battery per truck. This would eliminate the need to change batteries. A typical exception is the use of a push-pull on a loading dock of a high volume shipper as this may require a spare battery.

Battery maintenance and changing could easily be a one-hour discussion. However, it should suffice to say that it is not difficult or expensive compared to the benefits.

Chargers today are fully automatic. That is to say that once wired into a source of power, they should remain on indefinitely. The electric truck is plugged into the charger every night regardless of the day use. The charger will measure the state of charge in the battery and only charge as needed. This greatly increases the battery life as it eliminates over or under charging. Given proper watering and charging, the average battery life is five to seven years. It is very common to see batteries last over ten years. Remember that any charging area must be well lighted and well ventilated. An eye wash station must be within fifty feet and a spill cleanup kit should be readily at hand.

I believe that electric trucks are the finest, safest, most reliable, most comfortable, and by far the best way to clean up your forklift fleet.

Phil Hanford

Mid Columbia Forklift, Inc.

14th Annual Postharvest Conference,
Yakima, Washington
March 10-11,  1998

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