Technical Operation Of Internal Combustion And Electric Forklifts

Both internal combustion (IC) and electric forklifts are widely used, and ProLift's team offers expert support for both types of equipment.

Internal Combustion Forklift Operation

An engine converts chemical energy from fuel into mechanical energy, powering the forklift. Engines that operate on this principle are known as internal combustion (IC) engines and are commonly used in IC forklifts.

Since automobiles use similar engines, many people are familiar with their basic operation. However, forklifts utilize four distinct types of IC engines, each designed for specific applications.

Types Of IC Forklift Engines

• Gasoline engines use the same fuel as an automobile.
• Liquefied Petroleum Gas (LPG) engines run on a gas that occurs naturally. LPG is commonly used for gas grills.
• Compressed Natural Gas (CNG) engines use the same fuel supplied to homes and businesses to power stoves, furnaces and other appliances.
• Diesel engines use diesel fuel, a lower grade fuel not as refined as gasoline and therefore, not as combustible.

How An Internal Combustion (IC) Forklift Operates

Understanding the operation of an IC forklift helps operators and technicians better maintain and troubleshoot the equipment. Below is a clear breakdown of how the internal combustion engine powers the forklift.

1. Starting the Engine
   An ignition battery powers a gear-driven starter, which cranks the engine to begin the combustion process.
2. Fuel and Air Mixture
   The carburetor mixes liquid fuel with air to create a combustible mixture. This mixture is injected into the engine’s cylinders through a valve.
3. Combustion Process
   Inside each cylinder, a piston is connected to a rod, which attaches to the crankshaft. A spark plug ignites the compressed fuel/air mixture, causing an explosion. This explosion forces the piston and rod downward, generating mechanical energy.
4. Converting Energy to Motion
   The crankshaft converts the piston's downward motion into rotational energy, measured as revolutions per minute (RPM). Multiple cylinders are connected to the crankshaft, working together to maintain consistent power output.
5. Timing and Valve Control
   The engine block houses additional components, including the camshaft. The camshaft controls the precise opening and closing of the valves, synchronized with the engine’s RPM.
6. Powering Other Forklift Systems
   The crankshaft also drives the alternator or generator, which supplies electrical power to the forklift’s systems.
   Electricity generated in this process powers essential components, including: electrical components such as lights and sensors, power steering system for smoother maneuverability, and hydraulic pumps for lifting and tilting operations.

IC Forklift Application

An internal combustion (IC) forklift is ideal for applications requiring higher power output and where exhaust emissions are not a concern. It delivers strong torque for handling heavy loads on uneven terrain. IC models perform reliably in all weather conditions, including rain and snow, similar to a car.

Electric Forklift Motor

An electric forklift motor is a device that converts electro-chemical energy, provided by an industrial battery, into mechanical energy. An electric forklift motor must provide motion for the unit – forward, reverse, up and down – as well as power other items such as hydraulic pumps and electrical components.

Understanding Electric Forklift Parts And The Rule Of Magnetism

The operation of an electric forklift motor is based on the fundamental principles of magnetism, where opposite poles attract and like poles repel. To understand this concept, imagine a bar magnet mounted on a rotating shaft. When another magnet with the same pole is brought near, the like poles repel, causing the shaft-mounted magnet to move away while the opposite pole is drawn toward the approaching magnet. If the polarity is reversed, the motion continues as the magnet is once again repelled, creating continuous rotation.

Instead of relying on physical magnets, an electric forklift motor generates a magnetic field using electrical current supplied by an industrial battery. When wire is wrapped around an iron core and energized, it produces a magnetic field that behaves like a traditional magnet. By continuously reversing the electrical current, the motor creates controlled rotation, converting electrical energy into mechanical movement to power the forklift efficiently.

Electric Forklift Operation

• The field coil/stator acts as the magnet in your hand. Current runs into the wire in a single direction which determines this part has fixed north and south poles with the capability to repel opposite poles.
• The commutator/armature is the shaft-mounted magnet. Like the stator, it has a magnetic field formed when current is introduced to the wire wrapping. Since it can rotate it will move to try to match unlike poles to that of the stator.
• The brushes provide the reversing action similar to the action of turning the magnet on the shaft. The action of that reversal forced the rotating magnet away again as it attempted to realign unlike poles to those of the stator. The commutator reverses the polarity of the rotor continuously so that it will always act as an opposite pole to the fixed stator poles.

These processes generate smooth, powerful, and efficient mechanical energy, measured in revolutions per minute (RPM). In a forklift, the motor is directly connected to the drive axle without the need for a transmission or drive shaft. The splined, or grooved, end of the armature engages with the axle’s gear, controlling speed and power based on the electrical current supplied by the accelerator circuit.

Some electric forklift motors are designed to operate with either 36- or 48-volt batteries. A 36-volt battery is sufficient for most standard tasks, but when higher travel and lift speeds are required or when the forklift needs to operate for extended shifts, a 48-volt battery can be used with the same motor to provide additional power and efficiency.

Solid State Controls For Motorized Forklift Operation

The electric forklift's motor is part of the electrical system, which is managed by either a Silicon Controlled Rectifier (SCR) or Transistor Control. Acting as the "brain" of the forklift, this control system regulates several key functions. It determines the amount of current delivered from the battery to the drive motors through the accelerator circuits, ensuring smooth and efficient operation.

Optional solid-state controls can also manage the current supplied to the hydraulic pump circuits, enabling power steering, lift, tilt, and auxiliary functions. Modern solid-state controls feature built-in diagnostic capabilities, displaying fault codes when issues arise. Additionally, technicians can custom program these controls to adjust the forklift’s performance, optimizing it for operator convenience and specific application needs.

How Can We Help? ProLift service technicians are available for dispatch, supporting you with breakdowns and emergency service. Maintenance agreements are also available.