| Heitz Automotive Testing LLC |
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Brakes
Brake Actuator
The brake actuator is a linear-acting unit, using a 1/2 inch (13 mm) ball screw with integral load cell and position encoder.
It provides closed loop control of any profile for pedal travel, application force, brake line pressure, or vehicle deceleration. Profile commands can be from programs in either internal flash memory or SD card, or from external commands.
BNC signal connectors on the tray front panel are provided for output of force, pedal travel, trigger, deceleration and speed; and for an optional “start” input. BNC connectors on the power tray panel are used for input of speed, deceleration, and abort.
The trigger output is a relay closure which is activated by configurable pedal travel (e.g. 0.5 inch), for stopping distance tests.
A switch closure at the “Start” BNC input can be used to start/stop a program.
The system also has an optional thumb operated “Radio Switch” that attaches to the steering wheel. Using the Radio Switch for program start/stop allows the driver to keep both hands on the steering wheel and eyes on the road, for safety.
The brake actuator is a linear-acting unit, using a 1/2 inch (13 mm) ball screw with integral load cell and position encoder.
It provides closed loop control of any profile for pedal travel, application force, brake line pressure, or vehicle deceleration. Profile commands can be from programs in either internal flash memory or SD card, or from external commands.
BNC signal connectors on the tray front panel are provided for output of force, pedal travel, trigger, deceleration and speed; and for an optional “start” input. BNC connectors on the power tray panel are used for input of speed, deceleration, and abort.
The trigger output is a relay closure which is activated by configurable pedal travel (e.g. 0.5 inch), for stopping distance tests.
A switch closure at the “Start” BNC input can be used to start/stop a program.
The system also has an optional thumb operated “Radio Switch” that attaches to the steering wheel. Using the Radio Switch for program start/stop allows the driver to keep both hands on the steering wheel and eyes on the road, for safety.
Seat Frame
The system uses a reaction seat frame made up of stainless steel tubes. The front of the seat frame is secured by turnbuckles attached to modified front seat hold down bolts, or inserts in the seat rails. The rear of the frame is secured by a ratcheting belt and a “necklace” around the seat headrest. The frame is adjustable and is covered by a foam cushion.
A lower cross member of the frame has a bearing-mounted vertical stick, with a "pickle" switch handle at the top. The actuator attaches just below the pickle, to give a "knee-action" line to the brake pedal. When the system is not activated, the stick can swing forward, giving normal manual braking. Extension of the actuator applies the brakes. For easier driver entrance, the stick can easily be removed from the pivot to lower the actuator. The seat frame weighs 9 pounds
The pickle includes switches for “Energize”, “Start”, and “Throttle Engage” as well as a status indicator LED. The pickle Start switch is a third option to start/stop a program in addition to the front panel BNC input and radio switch described above.
The system uses a reaction seat frame made up of stainless steel tubes. The front of the seat frame is secured by turnbuckles attached to modified front seat hold down bolts, or inserts in the seat rails. The rear of the frame is secured by a ratcheting belt and a “necklace” around the seat headrest. The frame is adjustable and is covered by a foam cushion.
A lower cross member of the frame has a bearing-mounted vertical stick, with a "pickle" switch handle at the top. The actuator attaches just below the pickle, to give a "knee-action" line to the brake pedal. When the system is not activated, the stick can swing forward, giving normal manual braking. Extension of the actuator applies the brakes. For easier driver entrance, the stick can easily be removed from the pivot to lower the actuator. The seat frame weighs 9 pounds
The pickle includes switches for “Energize”, “Start”, and “Throttle Engage” as well as a status indicator LED. The pickle Start switch is a third option to start/stop a program in addition to the front panel BNC input and radio switch described above.
Pedal Brackets
Several pedal brackets are supplied. For automatic transmission vehicles the brackets are four or five inches wide, with face-mounted clevis and room for a foot. Vehicles with manual transmissions (which have little space between brake and accelerator pedals) have brackets with side-mounted rod ends, with the entire face for the drivers foot.
Brackets are secured to the pedals with vertically or horizontally mounted hose clamps.
Several pedal brackets are supplied. For automatic transmission vehicles the brackets are four or five inches wide, with face-mounted clevis and room for a foot. Vehicles with manual transmissions (which have little space between brake and accelerator pedals) have brackets with side-mounted rod ends, with the entire face for the drivers foot.
Brackets are secured to the pedals with vertically or horizontally mounted hose clamps.
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Operation
A configuration file selects the feedback to be used (actuator travel, actuator force, deceleration, line pressure). With the vehicle stopped and idling, the driver pulls back the pickle stick to the frame, then switches ON the energize switch. This energizes the brake power amplifier and momentarily resets the actuator travel encoder, setting the “zero” position. The Radio Switch, or the pickle switch, or the tray front panel switch can start a program. The radio and pickle switches are momentary. Press any switch to start, and press any switch to stop. The front panel Start switch can be configured to be momentary or on/off. |
Adaptability with Earlier Actuators
The Heitz-designed geared ball screw actuator used in earlier brake servo actuators can be used unchanged in System 4. Brake Performance Performance specifications depend on the motor used and the gear ratio used. Please see the specifications table below. |
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| with 23E Motor | with 23G Motor | with 28E Motor | |
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| Maximum Force 1,3 | 325 lb (1445 N) | 400 lb (1770 N) | 600 lb (2670 N) |
| No load speed 1 | 60 in/s (1520 mm/s) | 37.5 in/s (950 mm/s) | 33 in/s (838 mm/s) |
| Speed at 1000 N load 1 | 38 in/s (960 mm/s) | 25 in/s (635 mm/s) | 29 in/s (736 mm/s) |
| Stroke 2 | 7 inches (178 mm) or 5.5 inches ( 140 mm) | 7 inches (178 mm) or 5.5 inches ( 140 mm) | 7 inches (178 mm) or 5.5 inches ( 140 mm) |
| Retracted length (stroke dependent) | 16.5 inches (419 mm) or 15 inches (381 mm) | 16.5 inches (419 mm) or 15 inches (381 mm) | 16.5 inches (419 mm) or 15 inches (381 mm) |
| Installed weight (actuator + seat frame) | 14.5 lb (6.6 kg) | 14.5 lb (6.6 kg) | 15.5 lb (7.0 kg) |
Notes:
- With 2:1 gear ratio (motor shaft to actuator ball screw) and 0.5 inch lead of ball screw.
Other gear ratios can be made available. - Other stroke lengths can be made available. Changing this will also change retracted length and weight.
- Higher maximum forces are possible but only for brief time periods due to motor heating.
23E max force above is at 60% of maximum current
23G max force above is at 73% of maximum current
28E max force above is at 50% of maximum current