Sheargard Overload Clutches
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Sheargard Overload Clutches The Cross Sheargard clutch complements the range of Torque Limiters by providing machinery protection on applications where accurate torque control and shaft synchronisation are necessary; and when in the event of an overload, total disengagement of driving and driven members is required. The design of the Sheargard Clutches provides for the transmission of high torques (up to 125,000 Nm) with a compact, low inertia unit. Standard stock products enables prompt delivery, at low cost of shearpin chain sprockets and flexible shaft couplings. The provision of an optional motor monitor plate enables disconnection of the power supply and / or operation of alarm signals in the event of an overload when used in conjunction with a limit switch or proximity switch. The basic advantages of the well proven “Howdon” wedge shearpin, have been combined with a clutch designed for economic production, with component parts sized to enable the use of the existing range of torque limiter platewheel and chain flexible coupling to enable supply from stock of complete drive assemblies. For higher speed applications a rubber coupling is available. In the diagram Hub “ and Flange “B” have matching A” tapered slots cut axially in their periphery, into which the “Howdon” wedge-shaped shearpins “C” are inserted and firmly clamped by two self-locking screws. Torque is transmitted by the wedge which has a reduced diameter neck in mid-span “D”’ designed to shear when the pre-determined torque is exceeded, so allowing the sleeve to rotate freely on the hub. The Cross Sheargard by virtue of its design offers a number of advantages over alternate overload protection systems Simple Design Accurate Torque Ratings Email: sales@crossmorse.com In a Shearpin the full shear strength is directly available as a frictionless driving force. The use of up to three shearpins provides high torque capacity within a compact unit, keeping both inertias and costs to a minimum. Several ratings of pin for each clutch size provides over 200 stock torque ratings. The Sheargard can be used with chain sprockets, gears, belt drives or shaft couplings. In the event of an overload, the wedge shaped shearpins are easy to locate, and quickly replaced by removal of two self-locking screws and broken halves of shearpin, and replacement with a new wedge pin. Inaccuracy of torque setting in conventional shearpin couplings is caused by non-uniform shear necks, and poor fit of the pin with its mating surfaces. The “Howdon Wedge” pins are precision turned to a constant form and can be expected to fracture within ±10% of catalogue rating. The wedge pins are rigidly located in the mating grooves so totally eliminating fretting fatigue failures, and ensuring zero backlash making it ideal for indexing and reversing drives. The clamping of the pin into the wedge angle ensures positive radial and axial location. The design also ensures load sharing is achieved when a number of pins are used for higher torque drives, enabling different rated pins to be used in one clutch. The “Howdon Wedge” pins are naturally “fail-safe” under all conditions. They are not affected by changes in temperature or humidity and are tolerant of most environment conditions. Sizes 350-900SG standard pins are manufactured from brass to avoid sparking in the event of overload, thus making them suitable in volatile atmospheres. The unconventional shape of the wedge pins prevents the fitment of alien pins ensuring safety and product liability requirements are met at all times. The peripheral location of the wedge pins enables easy inspection, and clear colour coding of the pins ensures simple checking of torque setting. Cross Sheargard Clutches and Couplings are carried in stock with minimum pilot bore. Units can be finished bored and keyed to customer’s specifications through a 48 hour rework service. A large stock of standard rated wedge pins, colour coded according to capacity ensures instant spares availability. The cost of Sheargard Clutches is kept low by volume production techniques, so providing the customer with a low cost synchronised, reliable overload pr

Sheargard Overload ClutchesStandard Stock Sheargard Clutches are available in five sizes providing a torque range from 27 to 13,700 Nm. Other units with torque ratings to 125,000 Nm are available to order, on short lead time. For further details contact Cross & Morse Sales Office. Dimensions

Chain Coupling Dimensions Sheargard Flexible Couplings Sheargard Chain Couplings The standard Cross Sheargard unit combines with the Chain Coupling to provide stock overload couplings with minimum backlash and a high reliability. This construction provides a simple, reliable, easy to assemble flexible coupling capable of transmitting high loads and accommodating shaft misalignment with continuous overload protection. Motor monitor assemblies can also be used to switch off power in the event of an overload. Sheargard ES & KE Couplings For high speed drives (over 500 rpm) Tow inertia rubber...

Sheargard Torque RatingsSelection of Wedges for Torque Rating For each size of Sheargard clutch a selection of Standard wedge pins are available, which can be combined together to provide the desired torque setting. Standard Howdon wedges are coloured coded for identification. Sizes 350SG to 900SG use brass pins as standard (steel optional), other clutches use steel as standard pin material. Number of Wedges in Clutch Note:- Torque capacity of size 250SG controlled by unit size, and not wedge capacity. Sizes 1000SG and above are designed to accept up to four wedges, size 250SG only has two...