Gp and gv switch

Range and splitter shifting increase the number of ratios available from a main gearbox. The range unit switches between low and high ranges; the splitter divides a gear into two smaller steps. The design varies by gearbox: a range unit may use a planetary gear set, for example, while a splitter may be operated through a separate set of engagement teeth.

Manual ZF Ecosplit 16-speed gearboxes are among the transmissions fitted. Depending on the version, automated ZF AS-Tronic or TraXon gearboxes use different actuation and control systems. In Mercedes gearboxes, too, the design depends on the transmission type fitted and the shift-system generation. Range and splitter parts are therefore not interchangeable based solely on the number of gears.

When ordering, check the gearbox identification plate and the part version. Then compare the gear teeth, shaft diameter, shift sleeve fit, selector fork position and actuator connection, among other details. Parts must always be identified by transmission type; a visual comparison or selection based only on the model name is never sufficient.

A range unit that will not shift into high range, a splitter that sticks between two positions or a gear that jumps out under load does not necessarily have the same cause. Possible faults include leaking compressed-air lines, worn actuator seals, play in selector forks, damaged engagement teeth or worn synchroniser rings where fitted. In automated gearboxes, position sensors, electrical connections or an incorrect adaptation value can also prevent shifting. If the shift grinds mainly when warm or under torque, check the condition of the transmission oil as well.

For automated transmissions, first read the fault codes and live data, and note the driving position in which the problem occurs. Then use a pressure gauge to measure both the supply pressure and the pressure at the shift actuator during a shift command; compare both readings with the specifications for the gearbox fitted. Check lines and connections for pressure loss. Next, observe the actuator movement and compare the measured end positions with the specified values. During disassembly, measure play in the selector fork and shift sleeve with a feeler gauge or dial indicator, and inspect the engagement teeth and synchronisers for burrs and heat discolouration. Use only the tolerances in the documentation for the identified transmission type.

Do not replace only a damaged shift sleeve if the cause is a bent fork, an actuator with insufficient travel or a contaminated shift mechanism. If there is internal damage, also check the associated gears, shafts and rolling bearings, as well as for metal particles in the transmission oil. Fit new seals wherever the shift mechanism has been opened, and adjust the mechanism according to the manufacturer’s procedure. After assembly, perform a static function test and a road test under load; automated gearboxes may also require an adaptation procedure. This helps prevent recurring problems caused by a range unit that engages only partially.