Restraint system for use in a vehicle

A restraint system (1) for an amusement vehicle comprises a seat (2) for a user with a seat surface (20) and a backrest (21). A belt system (3) comprises a belt (30) (e.g., lap belt), a belt retractor (31), and a locking tongue (32) for insertion and locking in a belt buckle (4). Furthermore, a locking mechanism is provided which is designed such that the belt buckle (4) and the belt retractor (31) can be locked simultaneously and on both sides. The blocked belt (30) can subsequently be tightened by the operator via a special mechanism (5) (belt tensioner or take-up mechanism).