The MRC D-Cell is one of two cantilever brake that use brake pads with threaded mounting posts and one of the few that use linear springs rather than the industry standard coiled spring.
Mechanical explanation of the D-Cell. The arms are machined from billet aluminum with an arm height of 88.8mm. The arm is 16mm wide at the base through the mounting bushing, broadens to 22.1mm at 46mm from the arm bottom comprising the lower section. The arm narrows to 11mm at the top of the upper section. Most of the 1/2" (12.72mm) thick arm is milled away in two large triangular slots, this leaves an edge thickness of between 1.5mm and 4.5mm. Slots are also milled through the side of each wall. In the lower section it's done to make a passageway for the brake pad and it's holder.
A hole is drilled through the base of the arm for a machined brass bushing that is pressed and bonded in place. This bushing revolves on the mounting stud. As we mentioned, this brake uses a linear spring, which is a principle patented by WTB and licensed to MRC. It is made of a spring steel rod that is 2.35mm in diameter and 79mm long. The spring is held inside a machined aluminum cap that fits over the brass bushing. The cap has flat parallel sides spaced 14.3mm apart and a hole drilled through it for the mounting bolt. A small hole is drilled into the outer side of the cap to hold the spring which is bonded in place. This straight rod rises up to the top of the upper brake arm where a small steel bolt is threaded into the arm just below where the straddle grips the arm. The rod (spring) rests against the inner side of this bolt. When the mounting bolt is tightened, it holds the cap and rod stationary while allowing the arm to pivot smoothly.
The brake pad threads through an aluminum sleeve into a steel recessed nut. The nut is tightened from the outer side of the brake using a 5mm hex wrench. The milled slots in the lower arm section permit a range of pad position adjustments. The recessed nut has 6mm by 1mm threads tapped along its interior, and though it similar, the SRP recessed 6 x 1 nut will not work here because it the SRP version isn't long enough to reach the mounting post through the arm.
The D-Cell comes with a custom straddle cable that has a lead anchor at one end and uses a cable end clamp as the anchor for the other. The end clamp is made of machined brass rod with threads tapped through the interior. A set screw is turned down from each direction to grip the cable. Both arms have the same fittings for the straddle cable at the top, so either end of the cable will work in either arm. The D-Cell doesn't come with a cable carrier. MRC is involved in the marketing of a commonly designed and manufactured carrier with Russ Crystal of Crystal Designs called the G-Spot. The G-spot is sold separately. The D-Cell comes with two steel mounting bolts having a mushroom head with a 4mm hex fitting, 6mm by 1mm threads, a 12mm length and each weighs 3 grams. End of mechanical.
The brake pads included with the D-Cell are the Kool-Stop Eagle Claw 1's with a threaded steel mounting post. The brake pads with a convex steel washer that fits into a concave mounting post weighed 42 grams per pair. This brake had a Bike-Pro brake profile measurement of 21mm and can be used as either a front of a rear. The D-Cell weighed 122.5 grams (with 42 grams of brake pad and no cable carrier). With the 6 grams of mounting bolts it has a total weight of 129.5 grams. MRC anodizes the D-Cell in 8 colors, Blue, Black, Gold, Green, Lavender, Red, Silver or Turquoise (light blue). Made in USA
Color-B-BK-G-GN-L-R-S-T $ Price in Catalog
This brake is a variation on the D-Cell but was unavailable at time of writing but apparently has a compound straddle cable arrangement. More in later writing. The Linear D-Cell is available in Blue, Black, Lavender or Silver.
Color-B-BK-L-S $ Price in Catalog
This brake has a style of its own and is unique among all brakes because it uses a machined aluminum a scissored link arm between the brake arms to deliver simutaneous arm movement. Unfortuately this brake is made to fit U-Brake studs only The Power link is twist on the roller cam design in brakes. It is made of precision machined aluminum. Rather than a cable joining the end of each brake arm, the Power Link has two equal length, machined "bridge" or link pieces that revolve on precisely machined brass sleeves on the mounting stud. These bridge pieces are joined in the center with a pivoting brass bushing that incorporates a brake cable anchor bolt system. When the brake is installed, the brake wire is adjusted so the link pieces are pivoted down forming a "V". As the brake cable wire is drawn up, it pulls the bridge pieces so they are horizontal, which forces the brake arms apart and the brake pads to close around the rim. Direct linkage with firm positve braking. The Power Link comes with Kool Stop Eagle Claw pads and a MRC Power Link Flex-Plate. The Power Link weighs 153 grams, the brake pads add 47 grams, totaling 200 grams. The Flex Plate weighs 21 grams. The Power Link is available in Blue, Black, Lavender or Silver.
Color-B-BK-L-S $ Price in Catalog
