|| Used Forklifts
Glossary of Forklift Terminology
Inching, Inch Braking, or Inch Control
Inching is the process where an internal combustion engine lift truck moves slowly while the engine is operated at high speed to allow full speed operation of the lift truck hydraulic system. Inching is used when maneuvering the forklift and simultaneously lifting the forks. Inching occurs when the power shift transmission is partially disengaged at the same time the lift truck brakes are being slightly applied and is similar to “slipping the clutch” in a manual transmission Inching allows slow controlled movement of the forklift truck and is accomplished by simultaneous operation of the inch/brake pedal and the accelerator.
In today’s lift trucks, this overlap of transmission and brake is controlled by a single inch/brake pedal. Slight application of the inch/brake pedal allows for inching of the fork lift. Further application of the inch/brake pedal will completely disengage the transmission, fully apply the brakes, and bring he forklift to a complete stop.
Masts are specified by the type of mast, the lowered height, the lift height, and mast freelift. The mast lowered height is the height of the top of the mast from the floor when the mast is fully lowered. The lift height is the distance from the floor to the top of the upper fork surface when the mast is fully extended.
Masts are available as zero freelift, limited freelift, and full freelift. These freelift options are available in single, two stage, three stage, or four stage masts. The purpose of freelift is to allow lifting and maneuvering of loads in areas where overhead clearance may be restricted.
Freelift refers to the amount of vertical fork movement possible before the mast telescoping section begins to extend out the top of the mast. A zero freelift mast will begin to extend at the same time the forks begin to elevate. A limited freelift mast will allow for some fork movement, usually 12” to 14” before the mast sections elevate. A full freelift mast allows the forks to elevate to the top of the mast inner section before the mast sections begin to elevate.
2 Stage – Mast has two sections. The outer section is mounted to the lift truck. The inner section telescopes within the outer and elevates as the lift cylinders extend. The fork carriage rides within the inner section.
This type mast has a taller lowered height for a given lift height than an equivalent lift height 3 stage or a quad mast.
3 Stage - Mast has three sections. The outer section is mounted to the lift truck. The intermediate section telescopes with in the outer section. The inner section telescopes within the intermediate sections. Both the intermediate section and the inner section elevate as the lift cylinders extend. The fork carriage rides within the inner section.
These masts are usually equipped with a center cylinder to allow the fork carriage to elevate some distance before the mast sections begin to extend. This type mast provides a shorter lowered height for a given lift height than the 2 stage mast. 3 stage masts are usually used where overhead clearances, such as doorways, are a concern.
Quad – Mast has four sections. The outer section is mounted to the lift truck. The first intermediate section telescopes within the outer section. The second intermediate section telescopes within the first intermediate section. The inner section telescopes within the second intermediate section. The intermediate mast sections and the inner section extend as the lift cylinders extend. These masts are usually equipped with a center cylinder to allow the fork carriage to elevate some distance before the mast sections begin to extend. The fork carriage rides within the inner section.
Quad masts provide the shortest lowered height for a given lift height. These masts are usually used where severe height restrictions are present.
This is a very short two or three stage mast, generally with 60” of lift and an extended height of less than 84”, used on 4,000 lb. to 6,000 lb Class IV and Class V lift trucks for operation inside highway trailers where overhead clearance is restricted.
Forks and Carriages:
Forks come in two styles, hook type and pin type. Hook type are generally found on trucks up to 14,000 lbs. capacity. Pin, or shaft mounted, type forks are found on the larger capacity lift trucks.
Hook type forks are so named as the hook over and lock into the bars of the fork carriage. The forks can be installed by sliding the upper and lower hooks on to end of the carriage bars or through a special fork loading notch in the center of the lower carriage mounting bar.
Pin type forks mount to the fork lift carriage by means of the fork pin or shaft. The pin slides through an eye on the top of the fork and holds the fork to the fork carriage.
Forks sizes have been standardized within the industry and are load rated according to fork thickness and width. When replacing a fork, insure the new fork has the same load rating as the fork being replaced. The fork rating will be stamped on the shank of the fork.
Carriages have been standardized for hook type fork carriages. There are four sizes of hook type fork carriages rated by lifting capacity of the fork carriage.
Class I carriages are rated for loads up to 2000 lbs. The carriage bar spacing is 13 inches.
Class II carriages are rated for loads up to 5,550 lbs. The carriage bar spacing is 16 inches.
Class III carriages are rated for loads up to 10,000 lbs. The carriage bar spacing is 20 inches.
Class IV carriages are rated for loads up to 15,500 lbs. The carriage bar spacing is 25 inches.
Carriages for pin type forks will vary from manufacturer to manufacturer. Capacity of the carriage will be determined by the fork size and the carriage pin size. Pin mounted forks will also vary by the amount of offset between the fork and the fork eye.
Sideshift is the movement of the forks side to side. This is to assist in positioning the forks when picking up or depositing a load. Sideshift is normally used to insure the load is correctly centered on the forks without having to reposition the forklift.
Sideshift carriages are available on most forklift trucks and can be either “integral”, meaning they are part of the original equipment fork carriage, or “hang-on”, meaning they can be added later and mount on the original equipment fork carriage.
Sideshift carriages are available in a wide range of side to side movement. A normal sideshift would be 4” to 6” of movement to either side of the center of the forklift and would add 2” to the overall length of the forklift. The forks mount to the front of the sideshift carriage. Sideshift carriages are available for mounting of all types of forks.
Attaches to or is integrated as part of the carriage to allow 360 degree rotation of the forks or carriage attachment. Mostly used for inversion of drums or bins.
Bale clamps are used to handle any type of non-palletized baled products from cotton to aluminum cans. These attachments have two sliding arm that pick up the bales from the ends for transport and storage.
Carton clamps allow warehousing of larger items such as appliances or electronics. Space is saved by eliminating the need for pallets.
Drum clamps are designed to handle from one to four 55 gallon drums. Drum clamps can also be equipped with a rotator for emptying drums.
Specialty Forklift Attachments
Typically used to hold plastic or wooden bins to the forks when inverted by using a rotator.
Booms are available for the handling of carpet rolls or steel coils.
These are usually fork mounted attachment used for handling bulk materials. The hopper may be hydraulically powered or manually powered.
Fixed Fork Spreader:
Designed for handling wide loads such as trusses, rebar and pipe, the spreader has two extra forks to provide additional stability for the load.
Allows the fork carriage to be extended hydrauliclly to have greater reach.
Designed for unstable loads such as beverages, soft drinks, bottled water and empty containers. Load stabilizers allow faster operating speeds by securing the the palletized load.
These attachments may be fork mounted or carriage mounted. These usually have a capacity less than the load carrying capacity of the lift truck do to the extended load length of the jib.
Batteries & Chargers
Electric forklifts use industrial traction batteries. Forklifts in the USA will usually be equipped with batteries in the following voltages – 12v, 24, 36, and 48v. There are some forklifts being produced the use 72/80v batteries.
Electric forklift batteries are available in two general types: Flooded or Sealed. A flooded battery is one where water must be added regularly to maintain the electrolyte level in the battery. A sealed battery (also called “maintenance free” or VRLA) does not require the addition of water. Sealed batteries use a chemical reaction to maintain proper fluid level over the life of the battery.
Forklift batteries are sold by voltage, physical size, amp-hour capacity, and connector location. Check the forklift nameplate for the correct truck voltage, minimum battery weight, and maximum amp-hour capacity. Check the forklift Operating Manual for the correct battery specifications for your forklift.
A forklift truck can usually accommodate a wide range of different sized batteries. A battery should be selected to fit within the dimensions of the battery compartment. Most battery companies can provide a listing of batteries sizes that are recommended for your forklift truck.
In an electric forklift, the battery is used as the truck counterweight. The forklift lifting capacity is based on the battery being a specified minimum weight. Insure you use a battery that meets the minimum weight specified on the forklift nameplate. The battery minimum weight will be listed on the truck nameplate along with the maximum amp-hour capacity of the battery. Use these specifications when selecting a battery.
Battery chargers must be matched to the battery being charged. Always insure the charger is the same voltage as the battery being charged and that the charger has sufficient amp-hour capacity to charge the battery. The charger amp hour capacity should be within 10% of the amp-hour capacity of the battery being charged for the most efficient charging. Always insure the battery is connected to the charger before starting the charging cycle. Check the battery nameplate attached to the battery for information on the battery voltage, amp-hour capacity, and battery weight.
When charging a battery, insure the charger is the correct type for the battery you want to charge. An older charger built to charge only flooded batteries must not be used for sealed batteries or damage will occur to the battery and the charger. Most newer chargers can be used to charge all types of batteries and will be labeled to accept all batteries. Always check the instruction plate on the charger to insure it can accept the type of battery you want to charge.
For flooded batteries, only add water after the battery has been charged. This will prevent spattering of electrolyte out of the battery as the battery is being charged.
For best battery life, always keep the battery clean, and for flooded batteries, insure fluid levels are maintained. As a general rule, charge the battery and let the battery rest for an eight hour period before use. Do not discharge the battery below 80% of battery amp-hour capacity before recharging. Use an “equalizing” charge every fifth charge to insure all cells are maintained at the same voltage.
Electric forklifts can be equipped with a variety of devices that monitor battery use. These range from simple “gas” gauge meters to sophisticated “Battery Discharge Indicators” that will disable the lifting circuit and sound an alarm when the battery has been discharged to a preset level. These devices help to prevent battery and truck damage from severely discharging the battery during use.
Battery connectors come in two basic ratings – a small 175 amp rating and a larger 350 amp rating. Battery connectors are also available in different colors to be used to identify different battery voltages. Generally – red is used for 24V, grey for 36V, and blue for 48V. Other colors are available and may be used.
There are also different types of connectors. The two types generally used are the type SB and the type SBX. SB connectors are available in both 175 amp and 350 amp ratings and are the most common type of connector. The SBX connector is similar to the SB but contains additional contacts for use with auxiliary circuits on the forklift. On forklifts imported from Europe, the forklift may be equipped with a “DIN” connector which will not mate with the SB type connectors.
It is important when installing a battery in the forklift that the connector half attached to the battery is the same size and type as the connector half located on the forklift. Most connector types are “keyed” so different types of connectors cannot be mated to each other.
Warehouses may use guided aisles to guide the lift truck as it moves up and down the aisle. Guidance is usually used with Orderpickers and Turret trucks that are not normally turned to face the rack when working with loads. There are some instances where four wheeled trucks may be installed with a guidance system, but those applications are rare.
With this system, rails which are usually 3 X 3 angle iron which is bolted to the floor on each side of the aisle just in front of the rack face. This forms the guided aisle. The lift truck is then equipped with two guide rollers mounted to each side of the lift truck and spaced to just fit within the rails. The truck can now be placed into the rail and with the steer tire straight, can travel up and down the aisle without the operator having to steer the lift truck. This allows the operator to travel and lift/lower simultaneously without having to keep the truck in a straight line. This improves productivity and eliminates truck collisions with the racking.
With wire guidance, a wire is buried just below the surface of the warehouse floor in the center of the storage aisle. An electric current is run through the wire producing a magnetic field around the wire. The lift truck is equipped with special sensors at the front and rear of the truck that sense the magnetic field. A computer controlled guidance system on the lift truck uses the signals from the sensors to steer the lift truck and keep it centered over the guide wire.
Outside the guided aisle, the lift truck must be steered by the operator. When entering the guided aisle, the wire guidance system senses the wire in the floor and when the lift truck is correctly over the wire, the automatic steering system becomes active.
This system also allows the operator to travel and lift/lower simultaneously without having to steer the truck in a straight line. While a lift truck with this system is more expensive than a truck equipped for guide rails, using wire guidance saves the cost of installing and maintaining a guide rail system in the warehouse.
Fire and Electrical Hazard Labeling
Fork Lift trucks may be specifically labeled as to their acceptability for use in hazardous locations. A labeled truck indicates the design has met the minimum standards of ANSI/UL 558 for engine powered trucks or ANSI/UL 583 for electric trucks for the type label attached to the lift truck.
Applications for labeled trucks may be found in National Fire Protection Association NFPA 505 – Powered Industrial Trucks Including Type Designations, Areas of Use, Maintenance and Operation. Consult your local Fire Marshall and your insurance carrier for additional information on the approved uses of industrial powered trucks in your application.
The following labels may be attached to a forklift truck if the truck has been found to meet the criteria outlined in the two standards above. A labeled truck will have one of the following labels attached to the lift truck and the type designation will also be found on the lift truck nameplate.
Type “E” trucks meet the minimum standards for fire and electrical hazards.
Type “ES” trucks meet all the requirements of Type “E” trucks and have additional equipment to prevent the emission of sparks and limit the surface temperature of lift truck components.
Type “EE” trucks meet all the requirements of Type “E” and “ES” trucks and also have all electrical motors and spark producing electrical components completely enclosed.
Type “EX” trucks are specially designed for use in atmospheres where flammable vapors, fibers or dust may be present.
IC Engine Powered Trucks
IC engine powered trucks are labeled according to the fuel used to power the lift truck.
Type “G” trucks are gasoline fueled and meet the minimum standards for fire hazards.
Type “GS” trucks are gasoline fueled and meet all requirements of a Type “G” truck and have other equipment installed to the electrical system, fuel system, and exhaust system to allow them to be used in certain hazardous applications.
Type “LP” trucks are LPG fueled and meet the minimum standard for fire hazards.
Type “LPS” trucks are LPG fueled and meet all requirements of a Type “G” truck and have other equipment installed to the electrical system, fuel system, and exhaust system to allow them to be used in certain hazardous applications.
Type “G/LP” trucks are duel fuel units as they may be operated on gasoline or LPG without any alteration to the fuel system. Trucks labeled “G/LP” meet the minimum standards for fire hazards.
Type “GS/LPS” trucks are duel fuel units as they may be operated on gasoline or LPG without any alteration to the fuel system. These trucks meet all requirements of a Type “GS” or Type “LPS” truck and have other equipment installed to the electrical system, fuel system, and exhaust system to allow them to be used in certain hazardous applications.
Type “D” trucks are diesel fueled and meet the minimum standards for fire hazards.
Type “DS” trucks are diesel fueled and meet all requirements of a Type “D” truck and have other equipment installed to the electrical system, fuel system, and exhaust system to allow them to be used in certain hazardous locations.
Type “DY” trucks are diesel fueled and meet all the requirements of Type “DS” trucks and in addition do not have any electrical equipment installed. These use air starters and have provisions for limiting the temperature of truck components.
Cushion – Smooth profile, solid tire. The tread is bonded to a steel ring to form the tire. The tire is pressed on to a hub that is mounted to the lift truck. Normally used in smooth floor warehouse applications. These tires are available in various rubber or polyurethane compounds. A poly tire is a solid tire made of polyurethane instead of rubber. Poly tires are used in place of cushion tires in those applications requiring a higher tire load capacity or a lower steering effort than can be obtained with the cushion tire. Poly tires can be obtained in a variety of hardness ratings to meet individual application requirements. Narrow Aisle and Orderpicker lift trucks will typically use small diameter poly tires for the outrigger load wheels.
Pneumatic – Various tread patterns, filled with air. Mounted to multi-piece rims. May be foam filled for puncture resistance. Normally used in outdoor, rough surface applications.
Solid Pneumatic / Pneumatic Shaped Solid – Solid tire molded in the shape of a pneumatic tire. Has a soft rubber inner core to provide the ride of a pneumatic tire while providing the puncture resistance of a solid tire. Normally used in all types of applications to replace pneumatic tires.
Manual – Manually shifted transmission. Lift truck is equipped with a clutch.
Powershift – One, two, or three speed depending on the size of the lift truck. Trucks up to 6,000 lbs capacity normally use a single speed transmission. Trucks from 7,000 to 15,000 lb. capacity normally use a two speed transmission. Trucks above 16,000 lbs capacity normally use a three speed transmission.
Hydrostatic – Hydraulic drive. A hydraulic pump is driven by the lift truck engine in place of a transmission. Hydraulic power from the pump is supplied to hydraulic drive motors attached to the drive wheels to power the lift truck.
Column Mounted – direction control (forward /reverse) is mounted on the steering column.
Foot Operated – direction control (forward/Reverse) is controlled by shifting accelerator pedal side to side. Allows the Operator the change directions without removing hands from steering wheel.
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