Overview: the Strengths of Electric, Gas & Diesel Forklift Trucks
Read on as we describe the strengths and weaknesses of the three different ways to power your fork lift truck.
Advantages: Battery electric forklifts are the most environmentally friendly. They are fume free in operation, giving off no harmful emissions. They are also quiet in use, and due to the weight and concentrated mass of the battery, they are generally more manoeuvrable than engine powered equivalents, due to the battery weight acting as an effective counterbalance, enabling the forklift truck to be more compact in size. The cost of recharging the battery overnight on a low rate tariff is considerably less than replacing gas bottles or filling a tank with diesel fuel. Electric fork lift trucks are generally easier to drive than engine powered machines, because they only have an accelerator and a brake pedal. There is no clutch pedal or inching pedal, and the operator does not have to “rev” the engine for fast lift or hill starting. The maintenance and servicing costs of electric forklifts is considerably less than engine powered alternatives, since there are so few moving parts by comparison.
Disadvantages: Higher initial cost, because of the battery and charger. They are also unavailable for use while the battery is being recharged, unless additional batteries for multi-shift working are available. This adds further to the cost, and space must be found for the battery charging station, and a suitable means of changing batteries provided, at shift change-over. Electric forklifts need a better floor surface to work on because the higher point loadings on the axles and wheels can cause them to sink in shale or hard standing. Intensive use on gradients will flatten the battery rapidly, but this can be partially overcome by specifying extra heavy duty capacity. Battery recharging can be vulnerable to power cuts from the national grid in the middle of winter. It is still the case, that electric fork lifts are not really suitable for prolonged use outside in wet weather, because the damp atmosphere causes problems with wiring circuitry and electrical components. Maintenance and repairs/fault finding is not so easily done on a DIY basis compared with engine powered trucks. 3 Phase electricity needs to be installed at the work premises to charge electric forklift trucks.
Advantages: Diesel powered fork lift trucks are ideal for applications where they are mainly used outside. The exhaust fumes and diesel particulates escape easily to atmosphere and do not cause environmental or health and safety issues which would occur indoors. Nevertheless, exhaust catalysts and purifiers can reduce noxious emissions and make the machines acceptable for occasional indoor use. Diesel engines are more fuel efficient than LPG powered engines and can be run on red diesel and an average fuel tank of 50 litres of duty free diesel will last much longer than an 18 kg bottle of gas, in like-for-like usage. The higher torque of a diesel engine fork lift compared with an LPG truck makes them better on gradients and more powerful for towing duties or when used with a bucket on the forks for scooping aggregates, etc..
The performance of a diesel truck is usually superior to an electric alternative, with better acceleration and lift speeds. In addition, if hydraulic attachments are required, such as rotating clamps, hydraulic fork spreaders, forward tipplers, etc., there is no problem with shortage of battery capacity, which can be the case with an electric fork lift. The maintenance and servicing costs of a diesel fork lift are lower than a gas truck, because the engine componentry is of sturdier construction and they operate at lower “revs”, hence diesel engines have a far longer life before wearing out. When it comes to disposal, diesel forklifts usually have a higher residual value than LPG or electric machines. Diesel fork lifts are available for use at any time of the day or night. The fuel gauge indicates when the diesel tank needs topping up, and this can be done in a matter of minutes.
Disadvantages: They are noisier in operation, the exhaust fumes are off- putting to some people, and may trigger smoke alarms inside an enclosed building. Their bulkier size means they need more space to operate in, but this is not usually a problem when used outside. The initial purchase price is less than an electric fork lift but usually slightly more than an LPG powered machine. Maintenance costs are higher than an electric truck, but less than an LPG truck.
Advantages: Fork lift trucks powered by LPG (liquified petroleum gas) have long been popular, due to their competitive pricing and suitability for inside/outside usage and convenience for round the clock working. The engines are usually derivatives of car engines, and consequently parts are readily available at keen prices. “Compact” gas trucks are more manoeuvrable than “yard design” diesel fork lifts, due to the solid cushion tyres and compact chassis compared with larger diameter tyres and increased clearances around the wheel arches of diesel trucks. LPG powered trucks are quieter in use (dba levels at the drivers ear) than diesel alternatives and their exhaust fumes are less offensive than diesel fumes. Exhaust catalytic converters work more efficiently on higher temperature LPG spark ignition engines, than on diesel compression ignition engines. The performance characteristics of LPG powered trucks are usually superior to electric and diesel powered equivalents. Travel speeds, rates of acceleration, and lift speeds usually outperform their electric/diesel rivals because of better power to weight ratios and more responsive engines. The service weight of gas trucks is generally less than their electric and diesel stable mates. Vibration levels of LPG trucks at the driver’s seat are lower than diesel trucks but higher than electrics.
Disadvantages: Whilst they are the cheapest to buy new, their maintenance and fuel costs are the highest of the three types. As with diesel trucks, they need to be given a “winter service” with antifreeze.
Of the three types of propulsion, the residual values of LPG trucks is probably lowest compared with electric and diesel. Gas trucks have an annoying tendency to run out of gas without notice, and sometimes a long way away from the gas bottle store. There is not normally a fuel gauge to give the operator an indication of how much gas is in the bottle. When gauges are provided, they are usually in the bottle and not on the instrument display. Pressure switches, indicating that the bottle is nearly empty, only give between 5 and 20 seconds warning. On larger capacity trucks, dual bottles overcome thisproblem. As with diesel fork lifts, LPG machines are more prone to leaks from the engine and transmission and may not be acceptable internally in some applications e.g. pharmaceutical industry, food industry, etc. The exhaust fumes can leave an oily film of hydrocarbon particles on surrounding surfaces in extreme cases, where there is no ventilation.
Gas trucks and diesel forklifts require from the driver a higher level of skill compared with an electric counterbalance truck. The use of the “inching” pedal or clutch, when loading/off-loading vehicles, to enable slow traction speed and high lift speed is not necessary when operating an electric machine. Because they will still run when the engine is out of tune, LPG and diesel machines are mistakenly sometimes thought to be more reliable than electrics, but this makes them much more prone to abuse if they continue to be used and more serious problems then arise, due to lack of regular maintenance.