Brake Actuation

691 Brake Lock Sytems automates hydraulic braking pressure in the service brakes to supplement the vehicle's mechanical parking brake and provide extra holding in heavy-duty and high-frequency applications. The 691 Brake Lock significantly enhances vehicle holding capability while not interfering with normal service brake function.

The ZF 691 Brake Lock can be interlocked with other vehicle components/systems such as a power takeoff control, bus door or wheelchair lift to insure the brakes are locked whenever those components/systems are being utilized.

The ZF Electric Activated Brake Lock supplements the standard parking brake of a vehicle by using a portion of the hydraulic service brake system. The brake lock is installed directly into the vehicles service brake system. It is activated by the flip of a toggle switch located within reach of the vehicle operator. When the operator applies the brake pedal, the brake lock acts as a one-way check valve and holds pressure to the brakes until the lock is released. Service brake operation is not affected by the use of the brake lock.

Twist locks are functionally the same as lever locks. The differences being a twist lock has a rotary action handle and the push rod is sealed and lubricated in silicone grease for tough environmental applications. All twist locks include a low-pressure warning switch.

• Used to lock pressure in a single brake line
• Ideal for tough environmental applications, such as dirt and moisture
• Uses a sealed rotary action handle

These slave cylinders are available in a variety of special strokes, mountings, and capacities used for remote clutch and throttle actuation.

ZF Straight Bore Master Cylinders are single piston, stright-bore type with a return spring, and are available with or without an integral reservoir. Most cylinders are available as brake fluid or mineral base hydraulic oil models in a variety of mounting styles.

The single piston straight bore type master cylinder has been proving its usefulness since the early 1930's and is still in extensive use. 

• Provides natural pedal "feel" through hydraulic reaction
• Completely hydraulic - no vacuum or air assist required

By eliminating the equalizing port normally found on master cylinders, this cylinder offers simplicity, ease of bleeding and versatility. The lack of compensation port allows the cylinder to be used in a broad range of applications indiscriminative of volumetric output.

• Provides natural pedal "feel" through hydraulic reaction
• Two independent master cylinders and reservoir ports in a common housing
• Provides braking in the event either the front or rear brakes become inoperative
• Completely hydraulic - no vacuum or air assist required
• Uses a remote fluid reservoir for ease of monitoring fluid level
• Provides natural pedal "feel" through hydraulic reaction
• Completely hydraulic - no vacuum or air assist required

The ZF Boosted Dual Master Cylinder is used to Modulate output pressures up to 1500 PSI. This is used in conjunction with properly sized brakes using mineral base oils and booster oil from a standby pressure source such as that of a transmission. This unique integrated design can easily adapt to many dual systems to provide steering assist power braking with one pedal applied or full power braking with both pedals applied giving equally balanced brake pressure.

• Power-off braking through master cylinder
• Open center spool construction provides smooth brake modulation at all pressures
• Direct acting pistons provide pedal "feel" accurately representing brake pressures
• Balance piston seals fluid loss from one master cylinder side should the opposite side brake line become severed Reduced pedal force during steering assist braking

The compact size Hydraulic Power Brake Actuator is designed for use with vehicles that are equipped with an open center hydraulic system that can supply 0.7 to 4 GPM at 335 PSI to obtain the set brake limit pressure. It can be operated manually through the booster during power-off conditions.

ZF Hydraulic Power Brake Actuator combines a hydraulically boosted power section with a master cylinder section in a single unit. This valve uses mineral based hydraulic oil in both the booster and master cylinder sections. The master cylinder section is separate from the booster portion so an alternative fluid such as transmission oil can be used for the brakes.

ZF Master Cylinder type air/hydraulic actuator is the combination of conventional master cylinder and an air chamber. The master cylinder is single acting type with one piston. Air pressure is used to actuate a push rod in the air chamber. The push rod in turn moves the piston in the master cylinder which forces the hydraulic fluid into the system.

• Available with or without internal residual check valve
• Incorporates a conventional master cylinder
• Sealed diaphragm fluid reservoir
• Available for industrial and mobile applications

These air/hydraulic actuators are a combination of a fluid actuator and an air chamber. ZF designed them to take advantage of available pressurized air sources to produce hydraulic pressure. The stem seal actuator eliminates cup cutting by allowing the cups to move freely in the master cylinder without passing over any ports.

• Includes stroke indicator
• Available for industrial and mobile applications using hydraulic oil or brake fluid
• Internal valving design enhances bleeding process and extends normal service life of primary seal

ZF Remote Actuators are typically used to actuate a brake or clutch from two locations when two master cylinders are used. They prevent the transfer of fluid from one system to another system. These actuators are available in hand, foot, or hydraulically operated models. They can be used in combination with a remote reservoir to accommodate accessibility. Pressure intensifiers are ideal for applications where a low pressure hydraulic source is available and a small displacement of high pressure hydraulic fluid is required.