Technical communication requires shared vocabulary. A term meaning one thing to a manufacturer may mean something different to an end user. This glossary establishes common definitions for terms used throughout plastic dolly specification, selection, and operation.
A
Additive. A substance added to base polymer to modify properties. Common additives include UV stabilizers, impact modifiers, colorants, and reinforcing fibers.
Anti-static. A property reducing static electricity accumulation. Anti-static materials dissipate charge to prevent electrostatic discharge damage to sensitive components.
AS/RS (Automated Storage and Retrieval System). A computer-controlled system that automatically places and retrieves loads from defined storage locations.
Axle. The shaft on which a wheel rotates. May be fixed to the fork with the wheel rotating on the axle, or rotating with the wheel.
B
Bearing. A component reducing friction between moving parts. Wheel bearings support wheel rotation on the axle. Common types include plain, roller, and ball bearings.
Brake. A mechanism preventing wheel rotation. Brakes may be foot-operated, hand-operated, or automatic. Types include friction brakes and positive-lock brakes.
Bumper. A protective element absorbing impact at equipment edges. Bumpers prevent damage to equipment, loads, and contacted surfaces.
C
Capacity. The maximum load an equipment item can safely support. May be specified as static capacity (stationary) or dynamic capacity (in motion).
Castor. A wheel assembly including wheel, bearing, fork, and swivel mechanism. Also spelled “caster” in American English.
Castor fork. The frame holding the wheel and axle. The fork connects to the swivel mechanism or directly to the mounting plate.
Center of gravity (CG). The point at which an object’s mass is concentrated. CG location affects stability during movement and stacking.
Coefficient of friction. A dimensionless number expressing the ratio between friction force and normal force. Higher coefficients indicate greater friction.
Conductive. A material property allowing electrical current flow. Conductive dollies dissipate static electricity through floor contact.
Copolymer. A polymer formed from two or more different monomers. Copolymers may have properties different from either constituent homopolymer.
Corner radius. The curved transition at deck corners. Larger radii reduce injury risk and improve aesthetics but may reduce usable deck area.
Creep. Gradual deformation under sustained load. Plastics exhibit more creep than metals. Creep limits long-term load capacity below short-term capacity.
D
Dead weight. The weight of empty equipment excluding payload. Also called tare weight.
Deck. The platform surface supporting loads. The deck may be solid, perforated, or have raised features.
Deflection. Bending or displacement under load. Acceptable deflection limits depend on application requirements.
Density. Mass per unit volume. Polymer density affects both weight and some mechanical properties.
Dolly. A low platform on wheels for moving loads. Distinguished from carts by the absence of raised sides or handles in basic form.
Draft angle. The slight angle on vertical surfaces enabling part removal from molds. Typical draft angles range from 1 to 3 degrees.
Dynamic load. Load applied to equipment in motion. Dynamic loads include inertia effects from acceleration, braking, and vibration.
E
ESD (Electrostatic Discharge). The sudden flow of electricity between two objects at different electrical potentials. ESD damages sensitive electronic components.
Elastomer. A polymer with elastic properties, capable of significant deformation and recovery. Rubber and some polyurethanes are elastomers.
Entry. An opening allowing fork insertion for lifting. Two-way entry allows forks from two opposite sides; four-way entry allows forks from any side.
Ergonomics. The study of people’s efficiency in their working environment. Ergonomic equipment design reduces injury risk and improves productivity.
Euro pallet. A standardized pallet measuring 800mm x 1200mm, widely used in European logistics. Also called EUR pallet or EPAL pallet.
F
Fatigue. Material weakening from repeated stress cycles. Fatigue failure may occur at stresses below the material’s static strength.
FDA (Food and Drug Administration). US regulatory agency overseeing food safety. FDA requirements affect materials used in food-contact equipment.
Filler. Material added to polymers to reduce cost or modify properties. Common fillers include talc, calcium carbonate, and glass fiber.
Flexural modulus. A measure of material stiffness in bending. Higher modulus indicates greater stiffness.
Floor load. The weight per unit area applied to floors. Concentrated floor loads from castors may exceed allowable limits.
Fork pocket. An opening designed to receive pallet jack or forklift forks for lifting.
Friction. The resistance to relative motion between surfaces in contact. Rolling friction is generally lower than sliding friction.
G
Gate. The point where molten plastic enters a mold cavity. Gate location affects material flow and may leave visible marks.
Glass transition temperature (Tg). The temperature below which an amorphous polymer becomes rigid and brittle. Properties change significantly around Tg.
Gross weight. Total weight including equipment and payload.
H
HACCP (Hazard Analysis Critical Control Points). A systematic approach to food safety identifying and controlling hazards. HACCP requirements affect equipment selection in food handling.
Handle. A grip feature for pushing, pulling, or carrying equipment. Handles may be integral or removable.
Hardness. Resistance to surface indentation. Often measured on Shore A or Shore D scales for polymers.
HDPE (High-Density Polyethylene). A thermoplastic polymer with higher density and stiffness than LDPE. Used in some dolly applications.
Homopolymer. A polymer formed from a single type of monomer. Polypropylene homopolymer has different properties than polypropylene copolymer.
Hub. The center portion of a wheel containing the bearing.
I
Impact modifier. An additive improving resistance to impact damage. Impact modifiers typically reduce brittleness.
Impact resistance. The ability to absorb energy from impacts without failure. Usually measured by standardized drop or pendulum tests.
Injection molding. A manufacturing process injecting molten polymer into a mold cavity. The dominant manufacturing method for plastic dollies.
Interlock. A feature enabling connection between multiple dollies. Interlocking dollies form trains for towing.
ISO (International Organization for Standardization). An international standards body. Many dolly-related standards carry ISO designation.
K
Kanban. A scheduling system for lean manufacturing controlling material flow. Dollies often serve as kanban carriers.
Kingpin. The vertical pivot point of a swivel castor. The kingpin enables direction changes.
KLT (Kleinladungsträger). A standardized small load carrier used primarily in automotive supply chains. Dollies often interface with KLT containers.
L
Lean manufacturing. A systematic method for waste minimization without sacrificing productivity. Dolly systems support lean material flow.
Load distribution. The pattern of weight spread across a supporting surface. Uniform distribution creates less stress than concentrated loads.
Lock. A mechanism securing castor swivel or wheel rotation. Locks prevent movement during loading or positioning.
M
Melt flow index (MFI). A measure of polymer flowability when molten. Higher MFI indicates easier flow but may indicate lower molecular weight.
Modulus. A measure of material stiffness. Higher modulus means greater resistance to deformation.
Moisture absorption. The tendency of materials to absorb water from the environment. High absorption may affect dimensions and properties.
Molded-in color. Color integral to the polymer rather than applied to surfaces. Molded-in color cannot wear away.
N
Nesting. Stacking configuration where units fit inside each other. Nesting reduces storage volume for empty equipment.
Net weight. Weight of payload alone, excluding equipment weight.
Non-marking. A wheel property preventing marks on floor surfaces. Non-marking wheels use formulations avoiding material transfer.
NSF (National Sanitation Foundation). An organization establishing standards for products affecting public health. NSF certification indicates sanitation compliance.
O
Offset. The horizontal distance between castor swivel center and wheel center. Offset affects swivel behavior and caster shimmy.
OEM (Original Equipment Manufacturer). A company that produces equipment sold under another company’s brand.
P
Pallet. A flat transport structure supporting goods in a unit load. Dollies often interface with pallets or serve similar functions.
Payload. The goods carried on equipment, excluding equipment weight.
Polyethylene (PE). A thermoplastic polymer used in some dolly applications. Available in various densities (LDPE, HDPE, UHMW).
Polypropylene (PP). The most common polymer for plastic dollies. Available as homopolymer and copolymer grades.
Polyurethane (PU). A polymer used primarily in wheel treads. Provides good wear resistance and floor protection.
Pool system. A shared equipment system where multiple parties use common equipment managed by a pool operator.
R
Racking. Storage structures with horizontal levels for organized storage. Equipment dimensions must match racking specifications.
Recycled content. The percentage of material derived from recycled sources. May be post-consumer or post-industrial recycled content.
Reinforcement. Material added to increase strength or stiffness. Glass fiber is a common reinforcement for polypropylene.
Resin. The base polymer material before processing into products.
Rolling resistance. The force resisting wheel rotation during movement. Lower rolling resistance requires less push force.
S
Safety factor. The ratio of failure load to rated load. A safety factor of 1.5 means the equipment should fail at 150% of rated load.
Shore hardness. A scale measuring material hardness. Shore A is used for softer materials; Shore D for harder materials.
Shrinkage. Dimensional reduction during cooling of molded plastic parts. Shrinkage affects final part dimensions.
Stacking. Placing units on top of each other for storage. Stack ratings indicate maximum safe stacking height.
Static load. Load applied to stationary equipment. Static loads exclude dynamic effects from movement.
Swivel. A rotating mechanism enabling castor direction changes. Swivel castors turn to follow movement direction.
T
Tare weight. The weight of empty equipment. Same as dead weight.
Thermoplastic. A polymer that softens when heated and hardens when cooled, repeatedly. Thermoplastics can be remelted and remolded.
Tolerance. The acceptable variation in a dimension. Tighter tolerances cost more to achieve.
Tow coupling. A connection point for attaching dollies in trains behind a towing vehicle.
Tread. The outer surface of a wheel contacting the floor. Tread material affects rolling resistance, noise, and floor protection.
Tugger. A powered vehicle towing multiple dollies in a train configuration.
U
UHMWPE (Ultra-High Molecular Weight Polyethylene). A type of polyethylene with very high molecular weight, providing exceptional wear resistance.
UV stabilizer. An additive protecting polymers from ultraviolet light degradation. Essential for equipment exposed to sunlight.
V
Virgin material. Polymer that has never been processed before. Distinguished from recycled material.
W
Weld line. A visible line where two flow fronts meet during injection molding. Weld lines may be weaker than surrounding material.
Wheel. The rolling element contacting the floor. Wheels may be solid, pneumatic, or composite construction.
Wheel diameter. The outside diameter of the wheel. Larger diameters roll more easily over obstacles but increase equipment height.
Y
Yield strength. The stress at which a material begins permanent deformation. Loads below yield strength produce only temporary deformation.
Note: This glossary covers terms commonly encountered in plastic dolly specification, selection, and operation. Industry-specific applications may use additional specialized terminology.