Idlers and Pulleys
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Headdriven Central Motor Station Standard Idlers and Pulleys This product brochure presents a stateof-the-art range of standardised idlers and pulleys for belt conveyors. The solutions outlined in this document represent an extension to our portfolio of drum motors. They are also to be seen as independent products for belt conveyors in general. Interroll has developed the modular platform 7000 for both variants. It forms the basis for idlers and pulleys. Both products are designed for a diverse range of applications within the field of unit-load handling, an area in which the well-known...

Idlers The basis of the idlers is formed by an extruded aluminium profile developed specifically for use in belt conveyors. This profile is ribbed so as to achieve maximum bracing against bending with optimum use of materials. The outer diameter of the idler is cylindrical in shape over half the length at the centre. The geometry of the idler is conical on both sides over 1/3 of the idler length (K = 0.7 mm). The steel bearing journals, i.e. the shaft ends, are installed in the aluminium profiles using fitted keys in a forced fit to prevent rotation. Proper axial seating is achieved by...

Pulleys The pulley is identical down to the last detail to the idler described above. As required by customer specifications, a drive journal is merely manufactured on one side to allow existing bull wheels or geared motors to be mounted. All pulleys can also be supplied with lagging. A basic alternative to pulleys with mounted gearing is the Interroll drum motor, which combines space-saving design with competitive pricing. Please contact your Interroll sales consultant or one of the Interroll central offices listed on the back page for a separate catalogue featuring drum motors....

Aluminium profile Our extruded aluminium profiles made of AlMnSi are manufactured to high-precision standards due to the special production processes applied. The profile design offers optimum resistance against bending, while at the same time having the lowest possible mass. The idlers that are installed complete with journals are machined in a clamp, allowing very tight tolerances to be achieved. The runout accuracy ranges between 0.07 and 0.15 mm, depending on the roller length, thus eliminating the need for fine-balancing of the drums for the given areas of use. In addition to its...

Precision selfaligning ball bearings based on DIN Only precision self-aligning ball bearings based on DIN series 22 are used for the 7000 product platform. Tolerance limits exceeding those cited in the DIN standard are additionally specified by Interroll to provide consistent high-quality operation – among others for bearing clearance, lubrication and sealing. Bending of the axle, even over extended unit lengths, remains uncritical due to the use of these precision self-aligning ball bearings. All of these bearings implement sealing of design 2RS, and lubrication is designed for the entire...

Drive journals and axle journals Drive journals and axle journals are installed in the aluminium profiles with a machined force fit. A fitted key provides anti-rotation security, with axial fitting ensured by a patented steel clamp. After being pressed into the aluminium profiles, the drums are machined to their final dimensions, allowing extremely tight tolerances and precise runout accuracies to be achieved. The axle projection of the drive journal is always based on customer specifications, taking into account the individual dimensions of the specific belt section profile, or of the...

Bearing housings The bearing housings have two functions; they accommodate the self-aligning ball bearings, while simultaneously forming the universal interface to the customer profile. Threaded holes (M8 or M10) are drilled into the back of the bearing housings in an arc. This allows universal attachment of the idlers and pulleys, extremely convenient and with high stability to belt section profiles or tensioning devices. The bearing housings are precisionturned items. The outside diameter is always smaller than the drum diameter to allow optimum movement of the belt on the housing when...

Pulley lagging To minimise slip between the pulley and the belt, the pulleys can also be ordered with lagging. Pulley lagging is always an optional extra, for which wear has to be considered. To minimize wear, the preset belt tension has to be adjusted to the lowest level required. The type of belt has to be coordinated with the specification of the lagging. Tolerance and application parameters Runout accuracy: Up to RL 500 mm = 0.07 mm RL 500 mm – RL 1000 mm = 0.15 mm Possible tolerance class for axle and drive journals: IT7 Dimensional variation: DIN ISO 2768-m Temperature range: – 5 °C...

Key facts about belts The design of the belt idlers and pulleys must also be taken into account when selecting conveyor belts. Loading on the idlers and pulleys is influenced by three parameters: • The load to be conveyed • The conveying speed • Belt tension Belts with a 1% parameter of 5 to 12 N/mm are supplied for unit-load handling. Interroll recommends running idlers and pulleys with belts that have a 1% parameter of 5 to 8 N/mm. The set belt elongation (stretch) should not exceed a value of 0.3 %. An essential factor here is the tension of the actual belt. The belt tension necessary to...