Hydraulic direct drives are well adapted to the general conditions in mining and materials handling. Partly due to their enclosed motors, they easily withstand the industry’s dust, grit and widely varying temperatures.
For conveyors, however, hydraulic direct drives offer more specific advantages. Easily tailored to both task and load, they have a modular construction that simplifies design and installation. And once in place, they provide many ways to maximize conveyor uptime and minimize stresses on machinery, chains and belts.
Hydraulic direct drive systems consist primarily of a hydraulic motor and a drive unit, the latter comprising a fixed-speed AC induction motor and an axial piston pump. The drive unit provides a variable flow of oil to the hydraulic motor in response to a control signal, such that the motor’s speed can be adjusted for every conceivable need.
The result is that the conveyor can be run at any speed within its speed range – without restriction. This allows soft starting sequences that minimize belt stress, for example, but also fine positioning when inching the belt in forward or reverse to inspect or replace it.
Unlimited starts and stops
In a conveyor, of course, speed capabilities are closely intertwined with torque. Hydraulic direct drives are capable of starting up from rest with a full load, and of accelerating it under the most extreme load scenarios. This is ensured by the very high starting torque, which can also be maintained for an unlimited period of time.
The other side of the equation is hydraulic direct drives’ monitoring and limiting of torque. This function provides built-in overload protection, eliminating the risk of undue stress on conveyor components.