GBP-375-A Linear LVDT Gauging Probe Spring Loaded

The GBP-375-A Linear LVDT Gauging Probe from Harold G. Schaevitz Industries (HGSI) is a high-precision, spring-loaded AC LVDT position sensor designed for ultra-accurate dimensional measurement in industrial, laboratory, and metrology environments. As part of the GB Series Spring Loaded AC LVDT Gauging Probes, the GBP-375-A delivers exceptional repeatability and stability in a compact, pencil-style design ideal for precision gauging applications.

Engineered for applications requiring extremely fine measurement resolution, this sensor combines a non-contact electromagnetic sensing principle with a precision spring-loaded probe mechanism. The result is a reliable and repeatable measurement solution capable of detecting extremely small changes in displacement.

With a stainless steel housing, sealed construction, and robust mechanical design, the GBP-375-A is built to withstand the demands of industrial and laboratory environments while maintaining consistent performance over time.

AC LVDT Measurement Technology

The GBP-375-A operates as an AC Linear Variable Differential Transformer (LVDT), a highly accurate and reliable sensing technology widely used in precision measurement applications.

The sensor requires an external signal conditioner and operates with:

• Input voltage: 3 Vrms nominal

• Input frequency: 3 kHz nominal

When energized, the primary winding generates a magnetic field that induces voltages in two secondary windings. These signals are processed by a signal conditioner to produce a highly linear output proportional to the position of the probe shaft.

Because the sensing element operates without physical electrical contact, the LVDT provides long-term stability and repeatability unmatched by contact-based technologies.

Spring-Loaded Probe with Precision Guidance

The GBP-375-A features a spring-loaded probe shaft guided by a precision linear ball bearing assembly. This design ensures smooth, repeatable motion while maintaining accurate alignment between the probe and the internal sensing core.

A key feature of this design is the non-rotating probe shaft, which minimizes radial play and reduces the effects of side loading. This is critical in high-precision measurement applications where even small mechanical deviations can impact accuracy.

The spring-loaded mechanism ensures consistent contact with the measured surface, allowing the sensor to deliver stable and repeatable readings across repeated measurement cycles.

Exceptional Measurement Performance

The GBP-375-A is specifically designed for ultra-precise dimensional measurement applications. Key performance characteristics include:

• Non-linearity: Better than ±0.5% of full scale

• Repeatability: ≤ 0.000006 inches (0.15 µm)

• Sensitivity: Up to 3.8 mV/V per 0.001 inch (for ±0.100" range)

The extremely high repeatability makes this sensor ideal for applications such as:

• Statistical Process Control (SPC)

• Quality Control (QC)

• Metrology and dimensional inspection

These performance characteristics ensure consistent measurement results even in high-cycle or automated testing environments.

Measurement Range Options

The GBP-375-A is available in multiple stroke lengths to accommodate different measurement requirements:

• ±0.040 inches (±1.0 mm)

• ±0.100 inches (±2.5 mm)

• ±0.200 inches (±5.0 mm)

Each range is optimized to provide high sensitivity and resolution, allowing users to select the best configuration for their specific application.

Pretravel and overtravel are carefully controlled to protect the sensor and ensure reliable operation within the measurement range.

Rugged and Sealed Construction

The GBP-375-A is constructed from stainless steel and designed to perform in demanding environments. Key durability features include:

• IP65-rated sealing for protection against dust and moisture

• Fluoroelastomer bellows to protect internal components

• High resistance to shock and vibration

Performance ratings include:

• Shock resistance: 1000g (11 ms)

• Vibration resistance: 20g up to 2 kHz

This rugged construction ensures consistent performance in industrial environments where reliability is critical.

Long Operational Life

Thanks to its non-contact sensing principle and precision mechanical design, the GBP-375-A offers:

• Life expectancy greater than 10 million cycles

Unlike potentiometers or other contact-based sensors, the LVDT does not experience electrical wear, ensuring long-term stability and reduced maintenance requirements.

Flexible Mechanical Design

The GBP-375-A features a compact cylindrical design with a 0.375-inch (9.5 mm) diameter body, making it easy to integrate into tight spaces and precision fixtures.

The sensor includes:

• AGD #9 hardened tool steel contact tip

• Chrome-plated finish for durability

• M2.5 x 0.45 thread for interchangeable tips

This allows users to adapt the sensor for different surface types and measurement geometries.

Electrical Integration

The GBP-375-A includes an integral cable:

• 6.5 feet (2 meters) long

• Foil shielded with drain wire

• Polyurethane outer jacket for durability

The shielded cable design helps minimize electrical noise and ensures stable signal transmission in industrial environments.

The sensor is compatible with most conventional differential-input AC LVDT signal conditioners. However, the datasheet notes that ratiometric signal conditioning is not recommended, ensuring optimal performance when paired with appropriate electronics.

Operating Conditions

The GBP-375-A is designed for reliable operation across a range of environmental conditions:

• Operating temperature: 5°C to 80°C (40°F to 176°F)

• Thermal coefficient: < -0.01% per °C of full scale

These characteristics ensure stable performance even in environments where temperature fluctuations may occur.

Typical Applications

The GBP-375-A is ideal for high-precision measurement applications, including:

• Laboratory R&D and materials testing

• Industrial gauging test stands

• Factory automation and inspection systems

• Precision dimensional measurement and metrology

Its high repeatability and stability make it particularly well suited for applications where small changes in position must be accurately detected and measured.

Summary

The GBP-375-A Linear LVDT Gauging Probe is a high-precision, spring-loaded AC LVDT sensor designed for demanding measurement applications. With its non-contact sensing technology, precision-guided probe shaft, and rugged sealed construction, it delivers exceptional repeatability and reliability.

Whether used in laboratory metrology, industrial inspection, or automated testing systems, the GBP-375-A provides accurate and consistent position feedback in a compact and durable form factor.

For applications requiring ultra-precise dimensional measurement and long-term stability, the GBP-375-A offers a proven and dependable solution.