Forklift drive components transfer mechanical energy from the power source into motion, enabling the forklift to move. These components adjust the engine's revolutions per minute (RPM) to an optimal speed, ensuring smooth and efficient wheel rotation. Here’s an overview:
Forklift Transmission Operation
A transmission is a set of gears, including a change gear and a drive shaft, by which power is transmitted from the engine to the wheels.
- Torque Converter: A torque converter is a device that transfers mechanical energy from the engine to the transmission. Similar to one electric fan causing another to spin, the engine-driven impeller and stator push hydraulic fluid into the turbine, generating motion. As the turbine rotates, it multiplies engine power to drive the transmission components. Acting as a fluid-based clutch, the converter enables smooth and gradual power transfer without sudden jolts. This design allows the engine to run while keeping the forklift stationary when needed.
- Gear-Driven Charging Pump: This pump continuously supplies cooled, filtered oil to essential transmission components, ensuring smooth operation. The main hydraulic pump, mounted on the outside of the housing, is also gear-driven by the transmission, similar to the charging pump.
- Clutch Packs: A set of enclosed plates connected to the turbine shaft utilizes hydraulic pressure to engage specific transmission gears. This mechanism allows the forklift to shift between multiple gears, ensuring efficient power transfer from the engine. As a result, the transmission enables smooth forward and reverse movement.
- Parking Brake: This brake is operator controlled and locks the drive wheels by not allowing the other transmission components to rotate.
- Pre-Reduction Gears: These gears, located on the drive axle, multiply torque before final gear reduction at the wheel. This reduces brake pedal effort and provides for higher torque.
- Inching System: This system allows the operator to disengage the transmission using the inching pedal.
Forklift Drive Axle
The drive axle is responsible for receiving RPMs from either the internal combustion (IC) transmission or the electric drive motor and adjusting them to power the wheels. It functions as both a structural component of the frame and a support for the upright. As the main cross member, the drive axle connects to the open end of the frame, securing its sides. In some forklifts, the upright is mounted on the drive axle, which, due to its heavy-duty, hardened-metal casing, can support the full weight of loads.
Forklift Differential
The differential, a key component within the drive axle of both electric and internal combustion (IC) forklifts, is a system of gears that allows one wheel to rotate faster than the other. This function is essential when turning, as the inner wheel travels a shorter distance than the outer wheel. To maintain smooth operation, the differential adjusts the speed of each wheel independently, preventing the outer wheel from slipping, which could cause the forklift to skid outward. By distributing power separately to each wheel, the differential ensures stable traction and controlled movement during turns.
Forklift Brakes
Forklifts are equipped with various braking systems, with most relying on hydraulic pressure from a master brake cylinder connected to the brake pedal. Some models feature a vacuum or hydraulic power assist system to reduce the effort required to apply the brakes. Additionally, air brakes are commonly used on larger trucks for enhanced stopping power.
- Wet Brakes: Inside the drive axle, there are disc components similar to transmission clutches, which are continuously lubricated and cooled by transmission fluid. This design extends their lifespan, minimizing the need for replacements.
- Disc Brakes: Disc brakes consist of a rotor, caliper and friction pads. This type of brake is common on the front axle of most automobiles.
- Drum and Shoe Brakes: This brake consists of a drum, shoes and wheel cylinders. It is common to the rear brakes of most automobiles.
Forklift Tires
Forklift tires are included as drive components and may be classified into these basic groups:
- Pneumatic Tire: Pneumatic tires are available in both tube and tubeless varieties, both of which use air to absorb shock and support the load. They are suitable for various surfaces, with high-inflation tires ideal for hard surfaces and low-inflation tires better suited for rough terrain. The main risk associated with pneumatic tires is the potential for blowouts due to punctures.
- Cushion Solid Tire: This tire is constructed from solid rubber and securely vulcanized to the wheel for durability. Its low profile and flat tread design enhance lateral stability, making it ideal for use on hard surfaces. Cushion tire forklifts, featuring smaller frames, offer superior maneuverability in tight spaces compared to models equipped with pneumatic tires.
- Pneumatic Solid Tire: This solid rubber tire is less dense than solid cushion. The shape and profile resemble a pneumatic and provide similar performance under operating conditions where pneumatics would be punctured and destroyed.
- Poly Tire: Polyurethane tires are commonly used on narrow aisle and pallet forklifts due to their high load capacity. Their compact size allows for smaller diameter tires, making them ideal for fitting under racking or inside pallet openings.
Contact ProLift with your questions about forklift drive components! Our team can also support you with replacement parts, regular maintenance and additional service.
