Michigan State Brakes Certification Practice Exam

What function does a load sensing proportioning valve serve?

1. Decreases brake force in loaded conditions

2. Increases hydraulic pressure to rear wheels when loaded

3. Balances brake pressure between front and rear wheels

4. Distributes pressure evenly regardless of load

The correct answer is: Increases hydraulic pressure to rear wheels when loaded

The load sensing proportioning valve plays a crucial role in optimizing the braking system based on vehicle loading conditions. When the vehicle is under load, this valve adjusts the hydraulic pressure sent to the rear wheels. By increasing hydraulic pressure when the vehicle is loaded, it ensures that the rear brakes can adequately handle the extra weight without losing effectiveness. This adjustment is essential for maintaining proper brake balance. In heavy loading situations, without this feature, there could be a tendency for the rear brakes to lock up prematurely, leading to reduced control and increased stopping distances. Therefore, the load sensing proportioning valve improves safety by adapting brake performance to changing load conditions, allowing for better handling and stability during braking. The other provided options do not accurately describe the primary function of the load sensing proportioning valve in a braking system. Balancing brake pressure or distributing it evenly disregards the necessity of adjusting based on load, which is the fundamental purpose of the valve.