Overview of Cross Tensioners

Cross Tensioners are devices designed to provide constant tension to belts or chains in fixed-centre drives, improving performance and extending component life. They incorporate a spring mechanism that absorbs overloads and reduces vibration. These tensioners are used in various industrial applications including agricultural machinery, off-road vehicles, conveyors, packaging, and printing presses. They are constructed with precision and high-quality materials for durability in harsh environments.

Types of Cross Tensioners

Rotary Tensioner (Type RT)

• Provides up to 90° of usable tensioning action.
• Compact design conserves space and simplifies adjustment.
• Uses multiple alloy steel compression springs housed internally, eliminating exposed moving parts.
• Body made from aluminium diecastings with oil-impregnated sintered bronze bearings for smooth operation and durability in extreme temperatures.
• Optional stainless steel springs for corrosive environments.
• Tension levels adjustable via marks on the rotating arm; includes a locking pin hole for positional security.
• Can be combined with roller chain idler sprockets (Series CRT) for chain tensioning.

Linear Tensioner (Type LT)

• Provides fully automatic straight-line take-up with up to 43mm linear adjustment.
• Rectangular aluminium diecasting housing two hardened steel reciprocating shafts spring-loaded outwardly.
• All-metal construction with no rubber parts, ensuring resistance to harsh conditions.
• Oil-impregnated sintered bronze bearings for maintenance-free operation.
• Available with stainless steel shafts and springs for corrosive applications.
• Chain guides made from polyethylene replace the mounting block in chain tensioner series (CLT), available in standard (89mm radius) and compact (reduced radius) versions for space-limited installations.
• Rigid adjustment tensioners (Type CT) are also available.

Construction Details

• Frames: High-strength diecast aluminium with heavy wall sections and ribbing to prevent deflection; all mounting surfaces fully machined.
• Bearings: Oil-impregnated sintered bronze, press-fitted, requiring no lubrication.
• Springs: Multiple alloy steel compression springs, grease-lubricated for long life and quiet operation.
• Mounting: Single bolt required for mounting and tension adjustment.
• Adjustment Marks: Provided for easy tension setting.

Rotary Tensioner Series RT Specifications

Models RT1001, RT1002, RT2001, RT2002 provide torque ranges from 8-18 Nm to 20-34 Nm with detailed dimensional data for mounting and adjustment. Blind holes for location pins are provided for rapid positioning. Adjustment marks every 15° facilitate tension setting.

Linear Tensioner Series LT Specifications

Models LT1002, LT2002, LT3002 offer spring forces from 66 N to 400 N and travel distances up to 43 mm. Dimensions and mounting hole specifications are provided for precise installation.

Rotary Chain Tensioners (Series CRT)

• Designed for simplex, duplex, and triplex British Standard roller chains.
• Extend roller chain life by over 30%, especially for centre distances exceeding 40 times chain pitch.
• Provide angular movement of 45° with robust construction.
• Include blind location holes for quick positioning or additional torque resistance.
• Torque ranges from 8-18 Nm to 20-34 Nm depending on model and chain size.
• Mounting instructions emphasize installation on the non-driving strand near the larger sprocket, with tension set by adjusting and locking the fixing screw.

Linear Chain Tensioners (Series CLT)

• Based on LT series with aluminium mounting block replaced by UHMW polyethylene chain guides.
• Mounted on the unloaded chain strand in compressed condition to remove slack and automatically adjust as chain wears.
• Available in standard series with large radius guides for smooth, quiet operation and compact series with smaller radii for space-restricted applications.
• Suitable for simplex, duplex, triplex, extended pitch, and rollerless chains.
• Mounting requires flat, smooth surfaces parallel to the drive line; retained by a metric bolt with specific minimum distances from chain centerline.

Efson Fixed Chain Tensioners

• Use UHMW polyethylene circular guides mounted in a diecast aluminium frame with slotted adjustment for quick positioning.
• Economical option for applications not requiring automatic tensioning or with frequent speed changes and torque reversals.
• Can be used on reversible drives at low speeds and loads.
• Mount on the outside of the non-driving chain strand near the larger sprocket.
• Adjustment by bolt positioning in slot and rotation up to 45° from perpendicular to chain centerline.
• Detailed dimensional data provided for various chain sizes.

Critical Information and Best Practices

• Always mount tensioners on the non-driving strand of the chain or belt.
• Ensure mounting surfaces are flat, smooth, and parallel to the line of drive.
• Use adjustment marks and locking features to set and secure tension accurately.
• Choose stainless steel components for corrosive environments.
• Use appropriate tensioner type and size based on chain size, torque range, and available space.
• Regularly check tension and adjust as necessary to maintain optimal performance and extend chain or belt life.