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When the load pressure at port A changes, both the oil flow through the restrictor and the load pressure against the control spool change, too, and consequently also the return channel cross-section. This control function keeps the effective oil flow through the restrictor in the control spool and through the cross-section in the return channel constant, regardless of the load pressure. The front attachment drop rate is adjusted merely by the pre-stress of the control spring at the handwheel. This reduces the effective oil flow by relieving the control spring, since even a low load pressure will restrict the return channel cross-section.