Precision Planetary Gearheads
The primary reason to use a gearhead is that it makes it possible to control a huge load inertia with a comparatively small motor inertia. Without the gearhead, acceleration or velocity control of the load would require that the motor torque, and therefore current, would need to be as many times higher as the reduction ratio which can be used. Moog offers a selection of windings in each body size that, coupled with a selection of reduction ratios, provides an assortment of solution to productivity requirements. Each combination of engine and gearhead offers exclusive advantages.
Precision Planetary Gearheads
32 mm Low Cost Planetary Gearhead
32 mm Precision Planetary Gearhead
52 mm Precision Planetary Gearhead
62 mm Precision Planetary Gearhead
81 mm Accuracy Planetary Gearhead
120 mm Precision Planetary Gearhead
Precision planetary gearhead.
Series P high accuracy inline planetary servo travel will gratify your most demanding automation applications. The compact design, universal housing with precision bearings and precision planetary gearing provides great torque density and will be offering high positioning effectiveness. Series P offers exact ratios from 3:1 through 40:1 with the precision planetary gearbox highest efficiency and cheapest backlash in the market.
Sizes: 60, 90, 115, 140, 180 and 220
Result Torque: Up to at least one 1,500 Nm (13,275 lb.in.)
Gear Ratios: Up to 100:1 in two stages
Input Options: Meets any servo motor
Output Options: Outcome 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 for high speeds combined with the associated load sharing make planetary-type gearheads perfect for servo applications
The case helical technology provides increased tooth to tooth contact ratio by 33% vs. spur gearing 12¡ helix angle produces clean and quiet operation
One piece world carrier and end result shaft design reduces backlash
Single step machining process
Assures 100% concentricity Boosts torsional rigidity
Efficient lubrication forever
The large precision PS-series inline helical planetary gearheads are available in 60-220mm frame sizes and provide high torque, substantial radial loads, low backlash, substantial input speeds and a tiny package size. Custom variations are possible
Print Product Overview
Ever-Power PS-series gearheads provide the highest functionality to meet up your applications torque, inertia, speed and precision requirements. Helical gears give smooth and quiet operation and create higher power density while preserving a small envelope size. Available in multiple framework sizes and ratios to meet many different application requirements.
• Industrial automation
• Semiconductor and electronics
• Food and beverage
• Health and beauty
• Life science
Features and Benefits
• Helical gears provide more torque ability, lower backlash, and tranquil operation
• Ring gear slice into housing provides better torsional stiffness
• Widely spaced angular get in touch with bearings provide productivity shaft with great radial and axial load capability
• Plasma nitride heat treatment for gears for good surface wear and shear strength
• Sealed to IP65 to safeguard against harsh environments
• Mounting products for direct and easy assembly to hundreds 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 SPEED (RPM)6000
AMOUNT OF PROTECTION (IP)IP65
EFFICIENCY AT NOMINAL TORQUE (%)94 – 97
CUSTOM VERSIONS AVAILABLEYes
The Planetary (Epicyclical) Gear System as the “System of Choice” for Servo Gearheads
Consistent misconceptions regarding planetary gears systems involve backlash: Planetary systems are being used for servo gearheads due to their inherent low backlash; low backlash is the main characteristic requirement for a servo gearboxes; backlash is usually a measure of the accuracy of the planetary gearbox.
The truth is, fixed-axis, standard, “spur” gear arrangement systems could be designed and designed only as easily for low backlash requirements. Furthermore, low backlash is not an absolute requirement of servo-primarily based automation applications. A moderately low backlash is advisable (in applications with very high start/stop, forwards/reverse cycles) in order to avoid interior shock loads in the apparatus mesh. Having said that, with today’s high-resolution motor-feedback gadgets and associated movement controllers it is easy to compensate for backlash anytime you will find a adjust in the rotation or torque-load direction.
If, for the moment, we discount backlash, in that case what are the causes for selecting a more expensive, seemingly more technical planetary devices for servo gearheads? What positive aspects do planetary gears present?
High Torque Density: Compact Design
An important requirement of automation applications is high torque ability in a concise and light package. This huge torque density requirement (a high torque/quantity or torque/weight ratio) is very important to automation applications with changing huge dynamic loads to avoid additional system inertia.
Depending upon the number of planets, planetary devices distribute the transferred torque through multiple gear mesh points. This implies a planetary gear with say three planets can transfer three times the torque of a similar sized fixed axis “normal” spur gear system
Huge rotational (torsional) stiffness, or minimized elastic windup, is important for applications with elevated positioning accuracy and repeatability requirements; especially under fluctuating loading conditions. The strain distribution unto multiple equipment mesh points implies that the load is supported by N contacts (where N = amount of planet gears) hence increasing the torsional stiffness of the gearbox by component N. This means it noticeably lowers the lost action compared to an identical size standard gearbox; which is what’s desired.
Added inertia results within an more torque/energy requirement of both acceleration and deceleration. The smaller gears in planetary program cause lower inertia. Compared to a same torque score standard gearbox, this is a good approximation to say that the planetary gearbox inertia is certainly smaller by the square of the number of planets. Again, this advantage is certainly rooted in the distribution or “branching” of the load into multiple gear mesh locations.
Modern day servomotors run at high rpm’s, hence a servo gearbox must be in a position to operate in a trusted manner at high type speeds. For servomotors, 3,000 rpm is pretty much the standard, and in fact speeds are continuously increasing as a way to optimize, increasingly complex application requirements. Servomotors working at speeds in excess of 10,000 rpm aren’t unusual. From a score point of view, with increased quickness the energy density of the electric motor increases proportionally without any real size increase of the engine or electronic drive. Thus, the amp rating stays a comparable while just the voltage should be increased. An important factor is in regards to the lubrication at substantial operating speeds. Fixed axis spur gears will exhibit lubrication “starvation” and quickly fail if working at high speeds because the lubricant is certainly slung away. Only unique means such as pricey pressurized forced lubrication systems can solve this problem. Grease lubrication is certainly impractical as a result of its “tunneling effect,” where the grease, over time, is pushed away and cannot circulation back into the mesh.
In planetary systems the lubricant cannot escape. It is continuously redistributed, “pushed and pulled” or “mixed” in to the gear contacts, ensuring secure lubrication practically in any mounting posture and at any speed. Furthermore, planetary gearboxes can be grease lubricated. This feature is inherent in planetary gearing due to the relative motion between the several gears making up the arrangement.
The Best ‘Balanced’ Planetary Ratio from a Torque Density Point of View
For much easier computation, it is favored that the planetary gearbox ratio is an precise integer (3, 4, 6…). Since we are very much accustomed to the decimal system, we tend to use 10:1 even though it has no practical benefit for the pc/servo/motion controller. Essentially, as we will see, 10:1 or more ratios are the weakest, using minimal “balanced” size gears, and therefore have the lowest torque rating.
This article addresses simple planetary gear arrangements, meaning all gears are engaging in the same plane. The vast majority of the epicyclical gears used in servo applications will be of the simple planetary design. Determine 2a illustrates a cross-section of this sort of a planetary gear set up using its central sun gear, multiple planets (3), and the ring gear. The definition of the ratio of a planetary gearbox demonstrated in the shape is obtained immediately from the initial kinematics of the system. It is obvious that a 2:1 ratio isn’t possible in a straightforward planetary gear system, since to satisfy the prior equation for a ratio of 2:1, the sun gear would have to possess the same diameter as the ring equipment. Figure 2b shows sunlight gear size for several ratios. With an increase of ratio the sun gear diameter (size) is decreasing.
Since gear size affects loadability, the ratio is a solid and direct influence to the torque rating. Figure 3a displays the gears in a 3:1, 4:1, and 10:1 basic system. At 3:1 ratio, sunlight gear is huge and the planets happen to be small. The planets are becoming “thin walled”, limiting the area for the planet bearings and carrier pins, therefore limiting the loadability. The 4:1 ratio is certainly a well-well balanced ratio, with sunlight and planets getting the same size. 5:1 and 6:1 ratios still yield rather good balanced gear sizes between planets and sunlight. With larger ratios approaching 10:1, the small sun equipment becomes a strong limiting factor for the transferable torque. Simple planetary models with 10:1 ratios have very small sunlight gears, which sharply limits torque rating.
How Positioning Precision and Repeatability is Suffering from the Precision and Quality School 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 fact is that the backlash features practically nothing to do with the product quality or accuracy of a gear. Only the consistency of the backlash can be viewed as, up to certain degree, a form of way of measuring gear quality. From the application perspective the relevant issue is, “What gear homes are influencing the accuracy of the motion?”
Positioning precision is a measure of how exact a desired placement is reached. In a closed loop system the primary determining/influencing elements of the positioning reliability will be the accuracy and image resolution of the feedback system and where the situation can be measured. If the position is definitely measured at the final outcome of the actuator, the affect of the mechanical pieces could be practically eliminated. (Direct position measurement can be used mainly in very high precision applications such as for example machine equipment). In applications with a lower positioning accuracy need, the feedback transmission is generated by a responses devise (resolver, encoder) in the engine. In cases like this auxiliary mechanical components attached to the motor like a gearbox, couplings, pulleys, belts, etc. will affect the positioning accuracy.
We manufacture and design high-quality gears along with complete speed-reduction devices. For build-to-print custom parts, assemblies, style, engineering and manufacturing solutions get in touch with our engineering group.
Speed reducers and gear trains can be categorized according to equipment type and relative position of input and outcome shafts. SDP/SI offers a wide variety of standard catalog items:
gearheads and speed reducers
planetary and spur gearheads
proper angle and dual output right angle planetary gearheads
We realize you may not be interested in selecting a ready-to-use rate reducer. For anybody who want to design your own special gear train or rate reducer we give a broad range of accuracy gears, types, sizes and material, available from stock.
Precision Planetary Gearheads