Abstract: A process for reducing the carbonization of the heat exchange surfaces in a tubular heat exchanger of boiler steel which, in particular, within a unit for the thermal cracking of hydrocarbons to alkenes and while producing steam, carries out the rapid cooling of the cracking products after they leave the cracking furnace. After the tubular heat exchanger is cleaned and before it is returned to service, the sides of the heat exchange surfaces which come into contact with the cracking products are treated under reducing conditions until the greatest possible reduction of the Fe.sub.2 O.sub.3 on the surface to Fe.sub.3 O.sub.4 has taken place, without submicron Fe powder being formed.

Abstract: A motor-vehicle door latch bolt has a housing in which a door bolt is receivable and a latch fork formed with a seat and with at least one detent and pivotal on the housing between a locked position engaged around the bolt and holding it deep in the recess and an unlocked position permitting the bolt to move into and out of the recess. A support link pivotal on the housing carries a latch pawl pivotal into and out of a holding position engaging the detent and preventing pivoting of the fork into the unlocked position. A motor-driven crank rotatable adjacent the fork is coupled to the support link for pivoting the support link and retaining pawl as the crank rotates. An inner lever pivoted on an assembly pivot has an abutment and a detent, and is coupled to the latch pawl, and an outer lever pivoted on the assembly pivot has an abutment engageable with the inner-lever abutment, and is operable from outside the door.

Abstract: A motor-vehicle door latch has a bolt projecting from a support and movable by an actuator between an advanced and a retracted position, and a housing movable between an open, a partially closed, and a fully closed position. A latch fork can engage the door bolt to retain same and lock the door. The servoactuator can, when the bolt is engaged with the fork, move the housing between the partially and fully closed positions. A pawl pivots on the housing between a holding position retaining the fork in the latched position and a freeing position permitting the fork to move out of the latched position. A release lever on the housing displaces the pawl from the holding to the freeing position. A opening lever on the housing operatively engageable with the support is coupled to the pawl for moving it from its locked to its unlocked position on movement of the opening lever from a cocked to a rest position.