Determination of the right-angle gear

QB gear drive technical informations

ALL MODELS

INTRODUCTION

There are some crucial factors in choosing your right-angle gear drive, which you need to locate in the chapters we have summarized in this introduction.

The type of right-angle gear drive may have multiple types of PTOs, depending on motion requirements.
These can be: male shafts, cavity with traction through locking set or UNI 8953 grooved profile or anchors through locking sets, which are the standard types we manufacture.
You can have other types such as, for example, hexagonal cavities or DIN type grooved profiles or other types, by contacting the technical department to check the possibility of manufacturing items in the required size.
As already mentioned in the features of our innovative design, the use of larger bearings and gears (size being the same) has also allowed us to make shafts and hubs with considerably greater inside diameters. This enables us to be able to enlarge the output shafts and to make holes or grooves having greater inside diameters, so that we can take advantage of the increased transmission capacity thanks to the new design and are therefore fully available for special solutions.
You can find the arrangement and number of standard PTOs in the summary section of the constructive “Type”, which also shows the rotating directions of the various outputs, so that you can determine the correct distribution of the rotations, starting from the input axis (male or hollow shaft) which, to simplify, will be “A” and will rotate clockwise by convention.
We advise caution in checking the rotations of the various PTOs at output, since they depend on the position of the input gear (Crown).
These are shown in 3D.
It would be different if you consider the same rotating directions looking at the PTO from the front.

DETERMINATION OF THE RIGHT-ANGLE GEAR

Selecting the correct type of angle bevel gear is not simply a question of defining the power required in relation to rpm and the torque to be transmitted. It also involves defining the conditions under which the angle bevel gear will be used. Defining operating conditions involves taking into consideration a number of factor such as:

The type of operating cycle (intermittent, continuous)
Radial and axial loads on the shaft ends
Maximum and minimum temperatures
Ambient conditions (e.g. dust and dirt levels)
The type of lubrificant used

Use Table to define the Service Factor for your application.

Calculate the Rated Power (Pn); Pn = Pe (Horsepower) x Fs.

On Table A, use the output speed and the rated power (Pn) to select the angle gear size and transmission ratio required for your application.

Check that the radial Fr and axial Fa loads applied at the centre of the protusion of every single shaft does not exeed the values shown in Table B. In the case of hollow shafts you should consider the force applied at the same distance of male shafts.

Check that the operating temperature does not exceed -20°C ÷ +80°C.

With regard to speed multiplier ratios, we strongly recommend not exceeding 2000 rpm at input in the 1.5:1 ratio; 1500 in the 2:1 ratio; 1000 in the 3:1 ratio and 750 in the 4:1 ratio.

If the unit is to be used in very dusty conditions, protect the oil seal against direct exposure to dust to prevent abrasive damage which might shorten the working life of the unit.

HINTS FOR COMPILING THE PRODUCT CODE

After locating the right-angle gear drive you intend ordering, and to avoid mix-ups, transform it into the respective identifying Product Code that, when extended, is made up of 5 “fields”:

Field 1 - Constructive Form and Type

From Type no. 1 to no. 33, constructive forms are Standard whilst from Type no. 34 to no. 55, the constructive forms can be supplied on request.
Field 2 - Input Shaft (A)

When it is possible to order the Input Shaft (A) in two different diameters, indicate letter R if you want the one with the Major diameter whilst there will be no indication for the one with the smaller diameter.
Field 3 - Size

Our QB series gearboxes come in 8 sizes: 54 - 86 - 110 - 134 - 166 - 200 - 250 - 350
Field 4 - Input (A) with PAM Flange

When the blind hollow shaft is required on the input axis (A) for the assembly of an electrical motor, please state the required PAM Flange, specified in the various sizes.
Field 5 - Transmission Ratio

Our QB series gearboxes come in 5 Transmission Ratios: R 1:1 - R1:1.5 - R 1:2 - R 1:3 - R 1:4
For special lubrication requirements, if the gearbox must be mounted with the grease chamber, add letter “P” at the end of the Code (see Lubrication Section).

Examples of how the Code is Composed

LOAD CONDITIONS

You will have to make some considerations before choosing the most appropriate right-angle gear drive according to the power or torque it must transmit.

First of all, begin from the nominal value that the right-angle gear drive must ensure during its lifespan. The table A indicates the max powers (kW) and torques (Mt) recommended in relation to the number of rpms at which the load is applied. These values are considered with a safety factor that is never less than 3 for the right-angle gear drive’s weakest part, whether it refers to the bearings or gears or other drive gears such as splines or other. Everything is calculated for a minimum life of 5000 hours for parts subject to wear at a constant rotation speed of 1000 rpm on the slow axis. These parameters define what can be the rate of the right-angle gear drive inspections.

Consider that these rates are carried out with constant load conditions (Service Factor = 1) and with the maximum load allowed by the right-angle gear drive, with working conditions between -20° and +80° C. Under overload or low load conditions, the duration of the mechanical components does not have a linear proportionality. For example, it may last much less with an overload of 130 to 140% as compared to the nominal load. Likewise, if the load has a non-linear pattern the service factor will vary accordingly. On the contrary, a reduced load use of 80 to 90% lengthens the duration exponentially, especially the right-angle gear drive’s pitting.
The table summarizes how to locate the service factor based on the type of load applied and consequently by how much you can increase the heaviness of the load itself.

Table A and Table B show the 5 ratios available for each size. There are two rows of values for all sizes in the 1:1 ratios.
This differentiation is due to the size of input shafts A or D which, even if “normal”, withstand less transmissible torque or power as compared to the R “reinforced” ones.

This distinction was not present in the previous versions but became essential after the new design with the use of larger bearings and gears that, size being the same, have enabled the transmissibility of greater torques and powers, compelling us to review the differences found between reinforced shafts/grooved profiles and small standard shafts, no longer sufficient to exploit the entire power increase of the new project.

AXIAL AND RADIAL LOADS

A further verification that will be added to the foregoing considerations is that related to axial loads.

This type of load, that the right-angle gear drive will have to withstand, can result from certain components of the forces acting perpendicular to the right-angle gear drive’s axis by pushing or pulling the shaft.

The most common example is given by a belt’s tension load where a part of the radial force axially affects the shaft, which houses the pulley. There may be several conditions involved in the creation of axial forces, even the gears that generate axial forces as they rotate, made with spiral toothing.

The conditions of maximum axial load that the various right-angle gear drives can withstand are summarized in the axial loads table. This table shows, according to rotation speed, the radial force (example 1) and the axial force (examples 2 and 3) that the various right-angle gear drives can withstand, considering the radial load applied at a distance equal to half the protrusion of the shaft and, for hollow shafts, a maximum overhang of the point of application, the same as that of the respective model with the male shaft. As in the previous cases, these are maximum recommended values.

The values in the tables A and tables B with the red color stand for limit or non-preferential conditions. Hence, if you have to work under these load and rpm conditions, contact our technical department for greater safety.

Load examples

FITTING POSITIONS

LUBRICATION NOTES

When operating bevel gears at low rotation rates ( < 100 rpm ), inadequate lubrication of the internal organs can occur and consequently the use of the following supplementary applications is required, depending on the chosen fitting position:

Pos. 1

On the upper bearing (side C) a nilos ring must be fitted internally to create a sealed grease chamber and ensure adequate lubrication.
Pos. 2

Fitting position that does not require supplementary applications.
Pos. 3

On the upper bearing (side B) a nilos ring must be fitted internally to create a sealed grease chamber and ensure adequate lubrication.
Pos. 4

If operating with input rotation rates < 100 rpm, a double sealing ring must be used with grease chamber on the upper bearing column (side A).
Pos. 5

Fitting position that does not require supplementary applications.

In cases of continuous operation and Service Factor FS=1 (see table) with rotation rates > 600/700 rpm the use of a bleeder vent is recommended to avoid the formation of high pressure and foam, while for rotation rates above 1400 rpm the use of an external cooling circuit is recommended.