ثلاثة أرباع دواسة الوقود/باستخدام حوالي 75% من طاقة المحرك القصوى

In this context, "three-quarter throttle" refers to adjusting the engine's power output to approximately 75% of its maximum capacity. Throttle control is used to regulate the engine's speed and power, and setting it to three-quarter means you're not pushing the engine to its limit but maintaining a high level of performance without fully opening the throttle. This instruction is part of a process to properly break in a new engine or operate it under certain conditions, ensuring it's running at a high but not maximum speed, likely to avoid strain while still achieving efficient performance. It's important for the maintenance and longevity of the engine, allowing it to run smoothly and efficiently without overstressing it during this period.