1. Five generations

2. The basics

3. Side haul railway dry docks

4. Transfer systems

5. Hauling machines

6. Ship transfer machinery

7. Chains, rollers and maintenance

8. Bridles roller system

9. Difficult drydocking

10 Construction procedures

11. Restoration & enlargement

12. Vertical lifting vs. inclined ways

When a railway dry dock travels on a system of free rollers, the roller frames, which are made in sections 12 to 15 feel long, have some tendency to slip down the inclined ways gradually. Thus a diver must retrieve the outshore frames from time to time and place them at the inshore end of the system. If the rotation is not too frequent the inconvenience is acceptable, and it at least has the good effect of keeping he rate of wear even for all rollers.

The steeper the track gradient, however, the greater is the slippage; and if there is little or no tide, access to the outermost frames is difficult. In such cases, a special wire rope or chain bridle can be arranged, one end attached to the cradle and the other to the track, passing through the other frame train so that the half-speed behavior of the roller frames is precisely maintained.

Next: Difficult drydocking