This document describes synchronous servo geared motors with redundant brakes, manufactured by STOBER. These drive systems are designed for demanding movements, particularly in gravity-loaded axes, offering high precision, safety, and efficiency.
Function Description
The core function of these devices is to provide precise and powerful motion control through synchronous servo geared motors, integrated with a redundant braking system. This system ensures safe operation, especially in applications where loads are suspended or gravity-affected. The redundancy is achieved by combining the motor's internal brake with an additional ServoStop spring-loaded brake integrated into the motor adapter.
The ServoStop brake is an electrically actuated, spring-loaded brake designed for dry running. In its de-energized state, it engages using spring force, providing a failsafe mechanism. It is released by an electromagnetic DC coil before the motor starts. The braking process involves a switch-on time (t2B, release time) until the anchor plate detaches from the brake disc and is magnetically held. When switching off, a response delay (t11B) occurs until torque generation begins, and a link time (t1B) until the nominal braking torque is achieved.
The system is designed for diverse-redundant operation in accordance with EN ISO 13849-1, ensuring high safety integrity levels (up to PL e, SIL 3) when combined with STOBER SD6 drive controllers and SE6 safety modules. This combination allows for safe brake management, including Safe Stop 1 (SS1), Safe Stop 2 (SS2), Safely-Limited Speed (SLS), Safe Brake Control (SBC), Safe Direction (SDI), and Safely-Limited Increment (SLI).
The motors themselves feature a single-tooth coil winding method, contributing to a super-compact design and high copper fill factor, which enhances power density and reduces overall length. They are equipped with backlash-free plug-in couplings, enabling easy removal of the motor while the axis remains braked.
Important Technical Specifications
General Geared Motor Data (P, PH, PHQ, PK, PHK, PHQK, K series):
- M1Bstat (Static Braking Torque): Ranges from 8 Nm to 100 Nm across various series.
- i (Gear Ratio): Varies significantly by series, e.g., P series: 3–50, PHQ series: 5.5–88, K series: 4–97.
- M2acc (Maximum Acceleration Torque at Output): Ranges from 31 Nm (C series) up to 43000 Nm (PHQK series).
- Δφ2 (Backlash at Output): Typically 1–4 arcmin for planetary series (P, PH, PHQ, PK, PHK, PHQK), and 10–20 arcmin for helical/bevel series (C, F, K).
- ηget (Gear Unit Efficiency): Generally high, ranging from 90–97% depending on the series.
- Power Density: Varies from ★☆☆☆☆ (C, F series) to ★★★★★ (PHQ series).
- Backlash: Ranges from ★★☆☆☆ (C, F series) to ★★★★★ (P, PH, PHQ, PK, PHK, PHQK series).
- Shaft Load: Ranges from ★★☆☆☆ (C, F series) to ★★★★★ (PH, PHQ, PK, PHK, PHQK series).
- Torsional Stiffness: Ranges from ★★☆☆☆ (C, F series) to ★★★★★ (PHQ, PHK, PHQK series).
- Mass Moment of Inertia: Generally ★★★★☆ across most series.
- Helical Gearing: Standard feature across all geared motor series.
- Mounting Position: Any mounting position is generally supported.
- Output Bearing: Reinforced output bearings are optionally available for many series (e.g., P3–P9, PH3–PH5, PHQ4–PHQ5, K5–K8).
- Continuous Operation: Possible without cooling for some configurations.
Synchronous Servo Motor (EZ series) Data:
- MN (Nominal Torque): 0.4 – 77.2 Nm.
- M0 (Stall Torque): 0.44 – 94 Nm.
- Shaft Design: Solid shaft without feather key is standard.
- Encoders: Supports EnDat 3 (OCS), EnDat 2.2, EnDat 2.1, and Resolver.
- Cooling: Convection cooling is standard, forced ventilation is optional.
- Brake: Permanent magnet holding brake is standard.
- Certifications: CE, cURus, UKCA.
ServoStop Brake Technical Data (MB series):
- M1Bstat (Static Braking Torque): 8.0 Nm (MB23) to 400 Nm (MB53).
- J1 (Mass Moment of Inertia): 6.3 kgcm² (MB23) to 236 kgcm² (MB53).
- m (Mass): 8.5 kg (MB23) to 61 kg (MB53).
- ΔφB (Brake Backlash): 17.0 arcmin (MB53) to 32.0 arcmin (MB23).
- t1B,DC (Linking Time DC): 40 ms (MB23, 30 Nm) to 200 ms (MB53, 200 Nm).
- t1B,AC (Linking Time AC): 160 ms (MB23, 30 Nm) to 800 ms (MB53, 200 Nm).
- t2B (Release Time): 20 ms (MB23, 8 Nm) to 250 ms (MB53, 200 Nm).
- PO,B (Nominal Power): 26 W (MB23) to 86 W (MB53).
- PholdB (Holding Power): 26 W (MB23) to 50 W (MB53).
Usage Features
- Modular Design: The STOBER drive system (gear units, motors, cables, drive controllers) is modular and scalable, allowing for tailored, compact, and powerful machine concepts. It can be adapted to individual requirements across various industries.
- Single Source Responsibility: STOBER takes responsibility for the entire drive train, ensuring certified operating safety and maximum availability through a single contact partner.
- Gravity-Loaded Axes: The redundant brake solution is specifically designed for safety in applications with gravity-loaded axes, providing safe support of the load even in case of power outage.
- Backlash-Free Coupling: The ServoStop motor adapter features a backlash-free plug-in coupling, allowing for easy motor removal while the axis remains braked.
- Encoder Options: A wide range of encoders is supported, including EnDat 3 (One Cable Solution), EnDat 2.2, EnDat 2.1, and Resolver, offering flexibility for different application needs.
- Mounting Positions: Various mounting positions (horizontal, vertical downward, vertical upward) are supported, with specific lubricant filling volumes depending on the orientation.
- Direction of Rotation: The input and output shafts rotate in the same direction for inline geared motors, while right-angle geared motors can have input and output shafts rotating in the same or opposite directions depending on the specific model and output side.
- Oil Expansion Tank: Recommended for fast-running gear units with high input speeds and low gear ratios in mounting position EL5 to prevent oil from escaping.
Maintenance Features
- Lubrication: Gear units are filled with the specified amount and type of lubricant at the factory. Special lubricants for the food industry are available upon request.
- Brake Monitoring: Manual monitoring of brake wear is possible via air gap checks with a feeler gauge. Electrical release monitoring can also be implemented in the terminal box using a non-contact, wear-free proximity switch.
- Air Release Valves: Fitted as a standard feature for gear unit sizes C6 to C9 (helical geared motors) and K5 to K10 (helical bevel geared motors), independently of the installation position.
- Temperature Monitoring: Motors are equipped with PTC thermistors or Pt1000 temperature sensors for thermal winding protection. These sensors help prevent damage by ensuring the motor shuts down if maximum permitted winding temperatures are exceeded.
- Documentation: Detailed operating manuals for various product series and ServoStop motor adapters are available for download, providing comprehensive information on installation, operation, and maintenance.
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