Slide bushings - types and selection

Scope of application

Slide bushings are used in machine nodes operating in rotary or oscillating motion, where load transfer is required while reducing wear of structural elements. The use of bushings allows interchangeability of the wear element and regeneration of the seat without replacing the entire body.

In industrial practice, bushings made according to DIN 1494 and ISO 3547 are used, and in the case of cylindrical bushings made of solid bronze, also solutions according to DIN 1850 or the manufacturer’s documentation.

Types of sliding sleeves

Steel-bronze (bimetallic) bushings are most commonly used in the construction of heavy construction machinery. A bushing of this type consists of a bearing layer made of steel and a sliding layer made of bronze or CuPb alloy. This solution provides high load carrying capacity and resistance to dynamic and impact loads, while maintaining the interchangeability of the wear element. Bimetallic bushings require lubrication during operation.

Composite bushings with a PTFE sliding layer are used in applications with lower loads. Such a structure consists of a steel base, a porous bronze layer and a polytetrafluoroethylene-based sliding layer. These bushings have a low coefficient of friction and can operate with limited lubrication, but their shock resistance is lower than that of bimetallic bushings.

In large-diameter machines and in remanufacturing by the boring method, solid bronze bushings, usually made of CuSn or CuAl alloys, are used. These bushings can have lubrication grooves and customized dimensions depending on the operating conditions.

Bushing selection criteria

The selection of the sliding bushing should be analyzed in the context of the actual operating conditions of the node. Consideration should be given to the nominal diameter of the pin, the anticipated unit load, the nature of motion (continuous or oscillating), the presence of shock loads, operating temperature and lubrication conditions. Also important is the material of the body and the possibility of maintaining concentricity during the regeneration process.

For construction machinery operating in dusty conditions and under highly variable loads, it is recommended to use bushings with increased wear resistance and ensure regular lubrication.

Working clearance between pin and bushing

The radial clearance between the pin and bushing must ensure the formation of a lubricating film and the compensation of thermal and elastic deformations. Too little clearance leads to an increase in operating temperature and accelerated wear of sliding surfaces. Too much clearance causes knocking, accelerated wear and loss of concentricity.

In industrial practice, approximate values of radial clearance are adopted depending on the nominal diameter and the nature of the work. For diameters up to about 50 mm, a clearance of a few hundredths of a millimeter is used. In the range of diameters 50-100 mm, the clearance increases in proportion to the diameter and load. For diameters over 100 mm, the clearance should be selected individually, taking into account the deformation of the structure and the type of lubrication.

Socket bushing fit

The bushing should be installed in the socket with an appropriate indentation to ensure its immobilization during operation. The pressure must be selected so as to prevent the bushing from rotating in the body, while not causing excessive deformation.

Too little pressure leads to micromotion of the bushing and wear of the socket. Too much pressure can result in a reduction of the bushing’s inner diameter and a reduction of the working clearance after assembly. In remanufacturing practice, the press-in values should be selected according to the tolerances specified for the bushing holes.

Installation requirements and inspection

Before installing the bushing, the surface of the socket should be cleaned and free of burrs. The edges of the hole should be chamfered to facilitate installation. The bushing should be assembled using a press, ensuring axial guidance of the component. After assembly, the inner diameter of the bushing, ovality and concentricity of the regenerated holes should be checked.

Types of sliding sleeves – technical overview

Series	Type of construction	Basic material	Standard	Features
WB700 / WB800	Retractable bronze sleeve	CuSn8P	DIN 1494 / ISO 3547	Rhombic or spherical lubricating notches
WB702 / WB802	Retractable bronze sleeve	CuSn8P	DIN 1494 / ISO 3547	Full perforation of the sliding surface
WB802-T	Retractable sleeve with lock	CuSn8P	DIN 1494 / ISO 3547	Perforation + sealing
JDB	Solid bushing	Bronze as required	DIN 1850	Lubrication holes and grooves
BWG	Self-lubricating solid bushing	Bronze with inserts of solid lubricant	DIN 1850	Graphite inserts / solid lubricant
BWO	Sintered self-lubricating bushing	CuSn10 (sintered)	DIN 1850 / ISO 2795	Impregnated with oil
SBT (DU)	Multilayer PTFE	Steel + bronze + PTFE	DIN 1494 / ISO 3547	Operation without lubrication
SBT (DP4)	Multilayer PTFE	Steel + bronze + PTFE	DIN 1494 / ISO 3547	High wear resistance
DEX	Multilayer POM	Steel + bronze + POM	DIN 1494 / ISO 3547	Operation with periodic lubrication
SWPB	CuPb multilayer	CuPb10Sn10	DIN 1494 / ISO 3547	Lead-brown layer
STEEL	Steel bushing	C45 / 100Cr6	DIN 17200	Lubrication grooves and channels
Polymer-composite	Plastic sleeve	PTFE / POM / PA	per documentation	Self-lubricating / high-temperature