FUNCTION
DESIGN
INSTALLATION
TECHTIPAccessory Drive Tensioners
The Accessory Drive Tensioners
- Provides constant tension to the belt to eliminate slip or noise
- Dampens belt vibrations caused by engine firing
- Tunes the accessory drive system for proper function
- Maintains alignment of the belt
- Automatically adjusts for belt stretch and wear
Automatic tensioners using conventional, high quality round wire torsion spring construction are inherently better able to ‘balance’ this offset load internally within the tensioner than are alternate flat wire (‘clockspring’) tensioners. This can result in generally improved tensioner alignment & durability of torsion spring tensioners in these applications. These robust torsion spring tensioner designs also do not need anti-friction PTFE filler strips as most often must be used on flatwire tensioners.
Features
All brands of replacement automatic belt tensioners are not alike. Automatic tensioners that are specifically designed for the unique packaging & operating conditions of each engine & accessory belt layout configuration (‘application specific’) are recommended & highly preferred. When properly designed & applied, these belt tensioners will provide pre-determined (‘engineered’), constant tension & variable damping to the belt. The engineered output of these tensioners consistently maintain correct belt tension and help to dampen belt system vibrations, within the belt's replacement life.
The primary advantages of a well-designed automatic belt tensioner are:
- Maintains its correct alignment to the belt
- Automatically maintains correct accessory belt tension
- Automatically dampens normal accessory system vibrations
- Eliminates need to adjust / re-tension belts
- Prevents belt slip (noise / excessive belt wear)
- Optimizes life of belt
- Provides for indication of correct belt length
- Provides indication of excessive belt stretch (replacement)
- Improves belt system alignment
- Extends accessory system component life Litens® accessory drive tensioners provide:
- Equal or greater than Original Equipment quality and performance
- Custom, application-specific fit, form and function
- Quieter and smoother accessory drive operation
- Extended accessory drive component durability
- Constant ‘engineered’ belt tension
- Improved belt life
Design
What makes up a Litens Accessory Drive Belt Tensioner?
PULLEY BOLT:
Fastens pulley to arm. In some cases can also be used as a lift feature for belt installation.
DUST SHIELD:
Prevents contaminants from entering pulley ball bearing.
BALL BEARING:
Maintenance free and sealed for life.
PULLEY:
Steel or plastic construction, depending on application. Due to belt length considerations, pulley diameters are application specific.
FRONT PLATE:
Retains the complete tensioner assembly. Due to mechanical staking feature, tensioners are non-serviceable and cannot be disassembled safely.
THRUST WASHER:
Provides additional damping and alignment.
ARM:
Robust and precision aluminum diecasting. Transmits torque from spring to pulley to provide constant belt tension. Arm also provides environmental protection for internal components.
PIVOT BUSHING:
Self-lubricating, highly wear resistant polymer component. Function is to ensure proper tensioner arm alignment relative to belt and counters tilting.
SPRING SUPPORT:
An engineered, highly wear resistant polymer material that provides secondary damping for smooth timing drive operation.
SPRING
Critical part of tensioner. Designed to provide constant, trouble-free tension to belt for life of tensioner. Round wire design not affected by corrosion or coil-to-coil contact. Does not require a PTFE filler strip to prevent spring lock-up.
SPRING SUPPORT/DAMPING ELEMENT:
Provides primary damping for smooth tensioner and accessory drive system operation. Damping varies with spring torque for consistent level of damping throughout operating range. Engineered, highly wear resistant polymer.
SPINDLE or BRACKET:
Robust and precision aluminum diecasting with integral locating pin. Keeps the arm ‘true’ to belt. Provides a pivot center for arm and anchors spring. Ensures angular alignment or proper placement on engine. Other accessories or passages for engine coolant may be integrated
CAST LOCATING PIN:
Incorporated into the diecasting for exact Original Equipment fit and accuracy. The purpose of the pin is to accurately locate the tensioner on the engine and does not have torque transmitted through it, after the mounting bolt is torqued down.Represents typical construction
Installation
For safety, always disconnect battery and wear appropriate safety equipment before performing any work under the hood.- Always install tensioner per vehicle manufacturer’s guidelines.
- Look for Original Equipment belt routing diagram located under hood or on front support panel. If unavailable, make simple sketch to aid reinstallation prior to belt removal.
- Observe the method for lifting the tensioner away from the belt. Common methods are:
- - 3/8 or 1/2 inch square for an extension or breaker bar.
- - If lifting square is not present, the pulley bolt is designed to be used as a lifting feature. Bolt thread will be right or left in order to not loosen during lifting. Double check socket size to ensure proper fit to bolt.
- - A cast lug is utilized on some models as the lifting feature. Lifting is performed by using an open end wrench
- Be careful that wrench socket or breaker bar is properly seated and positioned to allow clearance when tensioner reaches load (end) stop. Otherwise, your hand may be pinched or the tool may be trapped.
- Lift tensioner arm in the direction away from the belt. Lower tensioner arm against the stop after removal of the belt.
- Tensioner is spring loaded. It can force the tensioner arm rapidly to stop position and cause personal injury or tensioner damage.
- Remove the tensioner mounting bolt and washer (if supplied) for reinstallation.
- Install new tensioner in the reverse order of removal.
- Install belt in the reverse order of removal.