Ground boring apparatus

摘要

A housing for electrical/electronic apparatus associated with the boring apparatus has a coolant flowpath for directing coolant fluid to cool the electrical/electronic apparatus and/or the housing. A relief coolant outlet port is closed by closure comprising fusible material which fuses at a predetermined temperature thereby to open the relief outlet port. The temperature at which the material of the closure fuses is lower than the temperature at which substantial thermal damage would occur to the electrical/electronic apparatus within the housing (typically at a temperature substantially at or below 200 DEG C).