The RP-Z Brake Disc Jaw Flexible Coupling integrates a drum-brake disc into the coupling hub for use with shoe-type braking systems. Retaining all characteristics of the standard RP jaw coupling, it covers torques up to 6,650 N·m and bore sizes to Φ130 mm, with multiple brake disc sizes available per coupling model.
The RP-Z coupling extends the standard RP jaw flexible coupling concept by incorporating an integrated drum-brake disc directly into one hub. This configuration is designed specifically for drive systems equipped with external shoe-type (drum) braking units — the arrangement widely used in lifting machinery, cranes, hoists, and industrial winches where a positive, controllable braking surface must be available on the drive shaft without resorting to a separate standalone brake drum assembly.
By combining the coupling and the brake drum in a single machined component, the RP-Z eliminates a separate coupling-to-drum adapter, reduces the total drive train length, and ensures perfect concentricity between the coupling bore axis and the braking surface. This is critical for shoe brakes: eccentric brake drums produce cyclical variation in braking torque, accelerating shoe wear and reducing braking predictability. The RP-Z hub geometry controls concentricity and runout to the same tolerance as the shaft bore itself.
Multiple brake disc sizes (D⊂0; × T) are available for each RP-Z coupling size, allowing engineers to match the brake disc to the required braking torque and thermal energy per stop independently of the coupling size. The elastomeric spider absorbs the dynamic torque spike that occurs at the moment of brake engagement, protecting both the motor and the load from impact loads that would otherwise shorten bearing and gear life.
| Model | Torque (N·m) | Speed (rpm) | D (mm) | d1max (mm) | d2max (mm) | E (mm) | L0 (mm) | P (mm) | Brake disc D0×T options |
|---|---|---|---|---|---|---|---|---|---|
| RP38Z | 190 | 9500 | 80 | 48 | 34 | 24 | 114 | 7.5 | 160×60 / 200×75 / 250×95 |
| RP42Z | 265 | 8000 | 95 | 55 | 42 | 26 | 126 | 9.5 | 200×75 / 250×95 / 315×118 / 400×150 |
| RP48Z | 310 | 7100 | 105 | 60 | 48 | 28 | 140 | 10.5 | 200×75 / 250×95 / 315×118 / 400×150 |
| RP55Z | 410 | 6300 | 120 | 70 | 55 | 30 | 160 | 12.5 | 200×95 / 250×95 / 315×118 / 400×150 |
| RP65Z | 625 | 5600 | 135 | 75 | 65 | 35 | 185 | 13.5 | 250×95 / 315×118 / 400×150 / 500×190 |
| RP75Z | 1280 | 4750 | 160 | 90 | 75 | 40 | 210 | 15.5 | 250×95 / 315×118 / 400×150 / 500×190 / 630×236 |
| RP90Z | 2400 | 3750 | 200 | 100 | 100 | 45 | 245 | 18.5 | 315×118 / 400×150 / 500×90 / 630×236 |
| RP100Z | 3300 | 3350 | 225 | 110 | 100 | 50 | 270 | 20.5 | 400×150 / 500×190 / 630×236 / 710×265 |
| RP110Z | 4800 | 3000 | 255 | 125 | 110 | 55 | 295 | 23.5 | 400×150 / 500×190 / 630×236 / 710×265 |
| RP125Z | 6650 | 2650 | 290 | 145 | 130 | 60 | 340 | 27.5 | 500×190 / 530×236 / 710×265 / 800×300 |
For applications requiring a disc-brake (caliper-type) interface instead of shoe brakes, see the RP-P disc brake coupling. The full range is available in the coupling catalogue.
🇩🇪 Germany — Crane Manufacturer
A crane OEM in Dortmund standardised on the RP-Z coupling across their 5–32 tonne overhead crane range. The integrated drum eliminated the concentricity issues they had experienced with separate brake drum adapters, and reported brake shoe life increased by approximately 40 % as a result.
★★★★★
"Consistent concentricity across every production unit — a level we could not achieve with separate components." — Quality Manager
🇲🇷 Morocco — Port Equipment
A port authority in Casablanca fitted RP-Z couplings on container crane long-travel and cross-travel drives. The multiple brake disc size options allowed the port engineers to upgrade the braking torque on two gantry cranes without changing the coupling size or modifying the motor mounting arrangement.
★★★★★
"The flexibility to choose the drum size independently of the coupling size saved considerable redesign time." — Equipment Engineer
🇵🇱 Poland — Mine Hoist Drive
A mining equipment supplier in Silesia specified RP-Z couplings on auxiliary hoist drives at a copper mine. The elastomeric spider proved effective in absorbing brake-engagement shock loads that had been cracking gear teeth in the previous rigid-coupling installation.
★★★★☆
"No gear damage since installation. The shock absorption makes a real difference in our application." — Mechanical Engineer
RP-Z is for shoe-type drum brakes: the integrated disc is a cylindrical surface against which curved brake shoes press from the outside. RP-P is for disc-type caliper brakes: the integrated disc is a flat annular plate that a caliper grips from both sides. The selection is determined entirely by the brake actuator type already specified in the drive system.
Each RP-Z size has a defined range of brake disc options (D⊂0; × T dimensions). You choose the brake disc size based on the required braking torque and thermal energy capacity, independently of the coupling torque rating. This flexibility is particularly useful when upgrading brake performance on an existing installation without changing the coupling size.
The order reference format is: [Size]Z-[D0xT] coupling [d1/d2], where D0 and T are the brake disc diameter and width in mm, and d1/d2 are the drive and driven bore diameters. For example: RP65Z-315×118 coupling 60/65. Please also specify the keyway dimensions and any sleeve-type requirements.
The polyurethane spider adds a controlled amount of torsional compliance between the brake drum surface and the driven machine. This dampens the impulsive torque spike at the moment of brake engagement, protecting gear teeth and bearings from impact loads. The spider does not affect the static holding torque capability of the brake, which is governed by the shoe actuating force and the drum-to-shoe friction coefficient.
The maximum bore in the standard RP-Z catalogue is 145 mm on the RP125Z model. For shaft diameters above this value, please contact us to discuss a custom engineering solution — larger bores are technically feasible but require individual structural evaluation.
RP supplies the RP-Z to crane OEMs, hoist manufacturers, and lifting-equipment distributors. Custom brake disc dimensions, bore specifications, and technical selection support are available. Browse the full jaw coupling range or the complete coupling catalogue.
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