Regardless of whether it was a progressive failure or a spontaneous failure thrust is a matter of pressure balance. Generally speaking thust bearing like steady state condition, they are hydrodynamically designed for a certain trust condition and do not tolerate rapid or excessive thrust loading. We have experienced both spontaneous and progressive thrust issues on our cutting pumps and the two predominant causes are progressive wearout due to erosive degradation, or rapid changes in flow to the process which is either due tothe valving switching suddenly or the cutting bit becomes plugged. To really nail the cause for you specific situation further information is required as trust bearing failure is almost always a symptomatic cause.
