Improved cable motivation towards duct exit

When the cable end is not far from the exit, the air flow there is relatively high, and this results in good cable motivation in such regions. The consequence of this is that the cable tension decreases between bends. Near the duct entrance the air flow is relatively slow (although the mass flow rate is everywhere the same) and this results in poor cable motivation. Thus in upstream regions the cable tension tends to increase, whilst in downstream regions it tends to decrease.