RAILWAY CONSTRUCTION. 59 



irregular manner, as compared to their smooth running when 

 following the leading or guiding influence of a bogie truck 

 in front. 



The wheel-base of a four-wheeled bogie truck for an engine 

 should always be greater than the gauge of the line over which 

 the bogie has to travel. On the 4 feet S inch gauge some of 

 the best results have been obtained with bogies having wheel- 

 bases varying from 6 feet to 7 feet. Where the wheel-centres have 

 been less than 6 feet, the running has been found to be much 

 less steady than with the wider spacing; and where the wheel- 

 base is not more than the gauge, there is a tendency for the 

 bogie to catch, or lock, when passing round sharp curves. 



