RKL4738 by Bosch Rexroth Indramat

The RKL4738 is a motor power cable manufactured by Bosch Rexroth Indramat within the RKL Motor Power Cables series. It transfers three-phase output from a drive controller to a servo motor while also carrying the auxiliary control lines needed for coordinated motion. By combining these circuits in one flexible jacket, the cable reduces the number of separate runs that must be routed through moving machine sections. This layout helps keep cable carriers organized in machining centers, gantries, and conveyor systems where repeated motion and limited space are common.

Its minimum bending radius during continuous flexing is 7.5 x D, so moving installations must respect that limit to reduce conductor stress. The cable has an outer diameter of 36.8 mm, which affects gland selection and the space required inside a drag chain. Each of the four power conductors has a cross-section of 50.0 mm² for high-current motor supply, while each control conductor uses 2.5 mm² for functions such as brake release or sensor power. Direct current resistance is 0.386 ?/km, which helps limit voltage drop on long runs. Lower resistance also helps reduce heat buildup when the cable is exposed to sustained inverter current.

The polyurethane jacket in RAL 2003 (orange) has a matte, adhesion-free surface that resists abrasion and coolant splash during industrial use. The power conductors are rated for 300/500 V, while the internal control pair is rated for 300/300 V, allowing power and auxiliary circuits to share the same cable body. In fixed installations, the conductor temperature can reach +90 °C, while dynamic applications are limited to +80 °C. The construction is halogen-free, which reduces corrosive gas formation during fire exposure. Its discharge capacitance of 1.3 nF/m also helps keep reactive current low during high-frequency inverter operation.