Oldham couplings and jaw couplings with standard keyways


Marlborough, Massachusetts, -- Ruland Manufacturing Co., Inc. now offers oldham couplings and zero-backlash jaw couplings with standard keyways as a stock item. Keyways increase the torque capacity of the coupling by creating a positive drive while also ensuring precise positioning of the coupling hub. The added torque capacity provided by the keyway may be needed in applications with shock loads due to sudden starts and stops or reversals,  when the bore is small relative to the coupling OD, when the shaft may be undersized, or when temperature changes may alter the size of the shaft or the bore in application. Precise positioning of the coupling hub may be needed in applications where phasing of the shafts is important for timing. 

Oldham couplings and jaw couplings are each three piece coupling assemblies comprised of two aluminum hubs with a mating center section for transmission of torque.   The three piece design has several advantages over single piece couplings including ease of assembly and the ability to conveniently mix and match hubs with different bores, even inch to metric combinations. 

Where oldham and jaw couplings differ markedly is in performance. Oldham coupling hubs have drive tenons that do not overlap when combined with the mating center disc. This design allows for easy sliding to accommodate misalignment with very light bearing loads since the only resistance caused by misalignment is frictional. The couplings also operate as a mechanical fuse since the hubs will spin freely if the center disc fails, and have the advantages of electrical isolation all at a relatively low cost. Oldham couplings offer zero backlash and high torque capacity. They accommodate angular and axial misalignment, but are especially useful in applications where parallel misalignment is present.

In contrast, zero-backlash jaw couplings have “jaws” that overlap when combined with their mating center spider. The couplings are thus fail safe in that the jaws will stay engaged even if the spider fails. Spiders are made of an advanced polyurethane material and available in three different hardness levels to provide varied levels of shock absorption. Ruland jaw couplings have a curved jaw profile and press fit to provide zero-backlash. Standoffs, located on the spider “limbs”, assist in angular misalignment capabilities, as well as electrical isolation. Jaw couplings are ideal for many servo applications with reversing torque since shock absorption, vibration dampening, and zero backlash are often required. 

Ruland oldham couplings and jaw couplings are offered from stock in a choice of six outside diameters from 1/2" (13 mm) to 2 ¼” (57 mm) in both set screw style and clamp style.  A large variety of inch and metric bore sizes starting at 1/8" (3 mm) is available with keyways offered on 3/8” (8 mm) and larger bores.

Oldham couplings and jaw couplings are part of Ruland’s complete product line which includes three additional types of zero-backlash motion control couplings: beam couplings, bellows couplings and miniature disc couplings, as well as shaft collars and rigid couplings.
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