Precision Planetary Gearheads
The primary reason to employ a gearhead is that it makes it possible to regulate a sizable load inertia with a comparatively small motor inertia. Without the gearhead, acceleration or velocity control of the load would require that the electric motor torque, and therefore current, would have to be as many times higher as the decrease ratio which is used. Moog offers a selection of windings in each frame size that, coupled with a selection of reduction ratios, offers an assortment of solution to end result requirements. Each mixture of engine and gearhead offers different advantages.
Precision Planetary Gearheads
32 mm Low Cost Planetary Gearhead
32 mm Accuracy Planetary Gearhead
52 mm Accuracy Planetary Gearhead
62 mm Accuracy Planetary Gearhead
81 mm Precision Planetary Gearhead
120 mm Accuracy Planetary Gearhead
Precision planetary gearhead.
Series P high accuracy inline planetary servo drive will meet your most precision planetary gearbox demanding automation applications. The compact style, universal housing with accuracy bearings and accuracy planetary gearing provides large torque density while offering high positioning efficiency. Series P offers actual ratios from 3:1 through 40:1 with the highest efficiency and lowest backlash in the industry.
Sizes: 60, 90, 115, 140, 180 and 220
End result Torque: Up to 1 1,500 Nm (13,275 lb.in.)
Gear Ratios: Up to 100:1 in two stages
Input Options: Meets any servo motor
Output Options: End result with or without keyway
Because of the load sharing characteristics of multiple tooth contacts,planetary gearboxes supply the highest torque and stiffness for just about any given envelope
Balanced planetary kinematics at high speeds combined with associated load sharing generate planetary-type gearheads ideal for servo applications
True helical technology provides increased tooth to tooth contact ratio by 33% vs. spur gearing 12¡ helix angle produces soft and quiet operation
One piece planet carrier and output shaft design reduces backlash
Single step machining process
Assures 100% concentricity Raises torsional rigidity
Efficient lubrication for life
The large precision PS-series inline helical planetary gearheads can be purchased in 60-220mm frame sizes and offer high torque, excessive radial loads, low backlash, huge input speeds and a small package size. Custom versions are possible
Print Product Overview
Ever-Power PS-series gearheads supply the highest efficiency to meet up your applications torque, inertia, speed and reliability requirements. Helical gears present smooth and quiet procedure and create higher electricity density while keeping a little envelope size. Available in multiple framework sizes and ratios to meet various application requirements.
• Industrial automation
• Semiconductor and electronics
• Food and beverage
• Health and beauty
• Life science
Features and Benefits
• Helical gears provide even more torque capacity, lower backlash, and calm operation
• Ring gear cut into housing provides higher torsional stiffness
• Widely spaced angular contact bearings provide productivity shaft with excessive radial and axial load capability
• Plasma nitride heat therapy for gears for excellent surface have on and shear strength
• Sealed to IP65 to safeguard against harsh environments
• Mounting products for direct and easy assembly to a huge selection of different motors
• Antenna pedestals
• Robotic actuation and propulsion
GEAR GEOMETRYHelical Planetary
Body SIZE60mm | 90mm | 115mm | 142mm | 180mm | 220mm
STANDARD BACKLASH (ARC-MIN)< 4 to < 8
LOW BACKLASH (ARC-MIN)< 3 to < 6
NOMINAL TORQUE (NM)27 – 1808
NOMINAL TORQUE (IN-LBS)240 – 16091
RADIAL LOAD (N)1650 – 38000
RADIAL LOAD (LBS)370 – 8636
RATIO3, 4, 5, 7, 10, 15, 20, 25, 30, 40, 50, 70, 100:1
MAXIMUM INPUT Acceleration (RPM)6000
DEGREE OF PROTECTION (IP)IP65
EFFICIENCY By NOMINAL TORQUE (%)94 – 97
CUSTOM VERSIONS AVAILABLEYes
The Planetary (Epicyclical) Gear System as the “System of Choice” for Servo Gearheads
Recurrent misconceptions regarding planetary gears systems involve backlash: Planetary systems are used for servo gearheads as a result of their inherent low backlash; low backlash can be the main characteristic requirement of a servo gearboxes; backlash is a way of measuring the accuracy of the planetary gearbox.
The truth is, fixed-axis, standard, “spur” gear arrangement systems can be designed and made simply as easily for low backlash requirements. Furthermore, low backlash isn’t an absolute requirement for servo-based automation applications. A moderately low backlash is advisable (in applications with very high start/stop, frontward/reverse cycles) in order to avoid inner shock loads in the gear mesh. That said, with today’s high-image resolution motor-feedback equipment and associated motion controllers it is easy to compensate for backlash anytime you will find a modify in the rotation or torque-load direction.
If, for the moment, we discount backlash, after that what are the reasons for selecting a even more expensive, seemingly more complex planetary systems for servo gearheads? What advantages do planetary gears offer?
High Torque Density: Small Design
An important requirement of automation applications is huge torque ability in a concise and light bundle. This high torque density requirement (a high torque/volume or torque/fat ratio) is important for automation applications with changing great dynamic loads to avoid additional system inertia.
Depending upon the number of planets, planetary devices distribute the transferred torque through multiple equipment mesh points. This means a planetary equipment with say three planets can transfer three times the torque of a similar sized fixed axis “typical” spur gear system
High rotational (torsional) stiffness, or minimized elastic windup, is very important to applications with elevated positioning accuracy and repeatability requirements; specifically under fluctuating loading conditions. The load distribution unto multiple equipment mesh points means that the load is backed by N contacts (where N = number of planet gears) therefore raising the torsional stiffness of the gearbox by aspect N. This implies it considerably lowers the lost motion compared to a similar size standard gearbox; and this is what is desired.
Added inertia results in an extra torque/energy requirement for both acceleration and deceleration. The smaller gears in planetary program cause lower inertia. Compared to a same torque ranking standard gearbox, it is a reasonable approximation to say that the planetary gearbox inertia is normally smaller by the sq . of the amount of planets. Again, this advantage is usually rooted in the distribution or “branching” of the strain into multiple equipment mesh locations.
Contemporary servomotors run at large rpm’s, hence a servo gearbox must be able to operate in a reliable manner at high insight speeds. For servomotors, 3,000 rpm is almost the standard, and in fact speeds are constantly increasing so as to optimize, increasingly complex application requirements. Servomotors running at speeds in excess of 10,000 rpm are not unusual. From a rating point of view, with increased acceleration the power density of the engine increases proportionally with no real size boost of the motor or electronic drive. Therefore, the amp rating stays about the same while just the voltage should be increased. An important factor is in regards to the lubrication at huge operating speeds. Set axis spur gears will exhibit lubrication “starvation” and quickly fail if operating at high speeds as the lubricant is normally slung away. Only particular means such as high-priced pressurized forced lubrication systems can solve this issue. Grease lubrication is usually impractical due to its “tunneling effect,” in which the grease, over time, is pushed away and cannot movement back into the mesh.
In planetary systems the lubricant cannot escape. It really is constantly redistributed, “pushed and pulled” or “mixed” in to the equipment contacts, ensuring secure lubrication practically in virtually any mounting placement and at any velocity. Furthermore, planetary gearboxes could be grease lubricated. This characteristic is normally inherent in planetary gearing due to the relative motion between the several gears creating the arrangement.
The Best ‘Balanced’ Planetary Ratio from a Torque Density Perspective
For a lot easier computation, it is preferred that the planetary gearbox ratio can be an specific integer (3, 4, 6…). Since we are so used to the decimal system, we tend to use 10:1 despite the fact that this has no practical advantage for the computer/servo/motion controller. Essentially, as we will see, 10:1 or higher ratios are the weakest, using the least “well balanced” size gears, and hence have the cheapest torque rating.
This article addresses simple planetary gear arrangements, meaning all gears are engaging in the same plane. Almost all the epicyclical gears found in servo applications will be of this simple planetary design. Shape 2a illustrates a cross-section of these kinds of a planetary gear arrangement using its central sun equipment, multiple planets (3), and the ring gear. This is of the ratio of a planetary gearbox proven in the determine is obtained directly from the initial kinematics of the machine. It is obvious that a 2:1 ratio is not possible in a simple planetary gear system, since to satisfy the previous equation for a ratio of 2:1, the sun gear would have to possess the same diameter as the ring gear. Figure 2b shows sunlight gear size for several ratios. With increased ratio sunlight gear size (size) is decreasing.
Since gear size affects loadability, the ratio is a strong and direct impact to the torque rating. Figure 3a displays the gears in a 3:1, 4:1, and 10:1 simple system. At 3:1 ratio, the sun gear is large and the planets will be small. The planets are becoming “skinny walled”, limiting the space for the earth bearings and carrier pins, consequently limiting the loadability. The 4:1 ratio is usually a well-balanced ratio, with sunshine and planets getting the same size. 5:1 and 6:1 ratios still yield quite good balanced equipment sizes between planets and sunshine. With bigger ratios approaching 10:1, the tiny sun gear becomes a solid limiting factor for the transferable torque. Simple planetary styles with 10:1 ratios have very small sunshine gears, which sharply restrictions torque rating.
How Positioning Reliability and Repeatability is Suffering from the Precision and Quality Course of the Servo Gearhead
As previously mentioned, it is a general misconception that the backlash of a gearbox is a way of measuring the product quality or precision. The truth is that the backlash has practically nothing to perform with the product quality or accuracy of a gear. Only the regularity of the backlash can be viewed as, up to certain level, a form of measure of gear top quality. From the application point of view the relevant query is, “What gear homes are influencing the precision of the motion?”
Positioning reliability is a way of measuring how specific a desired position is reached. In a shut loop system the primary determining/influencing elements of the positioning accuracy will be the accuracy and quality of the feedback machine and where the placement is measured. If the position is usually measured at the ultimate productivity of the actuator, the impact of the mechanical components can be practically eliminated. (Immediate position measurement can be used mainly in very high precision applications such as for example machine tools). In applications with a lesser positioning accuracy necessity, the feedback signal is made by a feedback devise (resolver, encoder) in the motor. In this case auxiliary mechanical components attached to the motor like a gearbox, couplings, pulleys, belts, etc. will effect the positioning accuracy.
We manufacture and style high-quality gears along with complete speed-reduction devices. For build-to-print customized parts, assemblies, design, engineering and manufacturing services contact our engineering group.
Speed reducers and equipment trains can be classified according to equipment type in addition to relative position of insight and productivity shafts. SDP/SI offers a multitude of standard catalog items:
gearheads and speed reducers
planetary and spur gearheads
correct angle and dual productivity right angle planetary gearheads
We realize you may not be interested in selecting a ready-to-use velocity reducer. For anybody who wish to design your individual special gear educate or velocity reducer we provide a broad range of accuracy gears, types, sizes and material, available from stock.
Precision Planetary Gearheads