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YRT Rotary Table Bearings

Features:

YRT precision rotary table bearing is a kind of bearing fixed by a bidirectional thrust bearing and a centripetal-guided bearing. They can support radial loads, axial loads from both directions and tilting moments free from clearance and are particularly suitable for bearing arrangements with high requirements for running accuracy，like rotary tables, millings heads and reversible clamps.Due to the fixing holes in the bearing rings, the units are very easy to fit.

The bearings are radially and axially preloaded after fitting.

Sealing/Lubricant:

YRT bearings are supplied with seals. YRT bearings are greased by a lithium complex soap grease and can be lubricated via the outer ring and L-section ring.

Operating temperature:

YRT bearings are suitable for operating temperatures from 30℃ to 120℃


Design and safety guidelines
Basic rating life:
Please contact us in relation to checking of the basic rating life .The speed ,load and operating duration must be given.

Static load safety factor:
The static load safety factor S0 indicates the security against impermissible permanent deformations in the bearing. It is determined as follows:
Static load safety factor :Cor Coa N
Basic static load rating according to dimension tables: For Foa N
Maximum static load on the radial or axial bearing.
Caution! In machine tools and similar areas of application,S0 should be ＞4

Limiting speeds:

The bearings allow the limiting speeds given in the dimension tables. The operating temperatures occurring are heavily dependent on the environmental conditions. Calculation is possible by means of a thermal balance analysis based on frictional torque data.

Frictional torque:

The bearing frictional torque MRL is influenced primarily by the viscosity and quantity of the lubricant and the bearing preload.

The lubricant viscosity and quantity are dependent on the lubricant grade and operating temperature. The bearing preload is dependent on the mounting fits, the geometrical accuracy of the adjacent parts, the temperature difference between the inner and outer ring, the screw tightening torque and the mounting situation.

Starting torque:

For YRT bearing, it must be taken into consideration that the frictional torque can increase by a factor of between 2 and 2.5 with increasing speed.

Accuracy of adjacent construction:

The adjacent construction should be produced in accordance with Figure and the tolerances must be in accordance with the tables starting on page. Any deviations will influence the bearing frictional torque ,running accuracy and running characteristics.


Requirements for the adjacent construction-YRT.
Legend to Figure:
1.Support over whole bearing height. It must be ensured that the means of support has adequate rigidity.
2.A precise fit is only necessary if radial support due to the load or a precise bearing position is required.
3.Note the bearing diameter D1 according to the dimension tables. Ensure that there is sufficient distance between the rotating bearing rings and the adjacent construction.
Geometrical and positional accuracy of the adjacent construction:

nominal shaft diameter d mm		Deviation d		Roundness Parallelism Perpendicularity t₂,t₂,t₈,
over	incl.	for tolerance h5 µm		µm
50	80	0	-13	3
80	120	0	-15	4
120	150	0	-18	5
150	180	0	-18	5
180	250	0	-20	7
250	315	0	-23	8
315	400	0	-25	9
400	500	0	-27	10
500	630	0	-28	11
630	800	0	-32	12
800	1000	0	-36	14

Geometrical and positional accuracy for shafts-YRT


nominal shaft diameter D mm		Deviation D		Roundness Parallelism Perpendicularity t₂,t₂,t₈,
over	incl.	for tolerance zone h5 µm		µm
120	150	+18	-7	5
150	180	+18	-7	5
180	250	+22	-7	7
250	315	+25	-7	8
315	400	+29	-7	9
400	500	+33	-7	10
500	630	+34	-7	11
630	800	+38	-8	12
800	1000	+44	-12	14
1000	1250	+52	-14	16

Geometrical and positional accuracy for shafts-YRT

Mounting dimensions H1、H2
	Figure 15 Mounting dimension H1、H２
L-section ring without support ring：
For the case “L-section ring without support ring”, the bearing designation is :YRT
L-section ring with support ring:YRT bore diameter VSP
For the case “L-section ring with support ring”, the bearing designation is :YRT VSP
Caution! For bearing arrangements with a supported L-section ring , only bearings with the suffix VSP、EB or T52EA can be ordered. If the normal design is mounted with a supported L-section ring, there will be a considerable increase in the bearing frictional torque .The support ring should be at least twice as the shaft locating washer of the bearing.


Fitting:
Retaining screws secure the bearing components during transport, For easier centring of the bearing ,the screws should be loosened before fitting and either secured again or removed after fitting. Tighten the fixing screws in crosswise sequence by using a torque wrench in three stages to the specified tightening torque MA, rotating the bearing:
Stage 1 40% of MA
Stage 2 70% of MA
Stage 3 100% of MA
Observe the correct grade of the fixing screws.
Caution! Mounting forces must only be applied to the bearing ring to be fitted, never through the rolling elements. Bearing components must not be separated or interchanged during fitting and dismantling. If the bearing is unusually difficult to move ,loosen the fixing screws and tighten them again in steps with a crosswise sequence. This will eliminate any distortion. Bearings should only be fitted in accordance with ,Fitting and Maintenance Manual.

YRT Dimensional tolerances, mounting dimensions, axial and radial runout YRT

Dimensional tolerance				Mounting dimensions					Axial and radial runout
Bore		Outside diameter		H₁ mm	ΔH_1s mm	Restr- icted ΔH_1s mm	H₁ mm	Restr- icted ΔH_1s mm	Stan- dart µm	Restri- cted µm
d mm	Δd_s mm	D mm	ΔD_s mm	H₁ mm	ΔH_1s mm	Restr- icted ΔH_1s mm	H₁ mm	Restr- icted ΔH_1s mm	Stan- dart µm	Restri- cted µm
50	-0.008	126	-0.011	20	±0.125	±0.025	10	±0.02	2	1
80	-0.009	146	-0.011	23.35	±0.15	±0.025	11.7	±0.02	3	1.5
100	-0.01	185	-0.015	25	±0.175	±0.025	13	±0.02	3	1.5
120	-0.01	210	-0.015	26	±0.175	±0.03	14	±0.02	3	1.5
150	-0.013	240	-0.015	26	±0.175	±0.03	14	±0.02	3	1.5
180	-0.013	280	-0.018	29	±0.175	±0.03	14	±0.025	4	2
200	-0.015	300	-0.018	30	±0.175	±0.04	15	±0.025	4	2
260	-0.018	385	-0.02	36.5	±0.2	±0.05	18.5	±0.025	6	3
325	-0.023	450	-0.023	40	±0.2	±0.05	20	±0.025	6	3
395	-0.023	525	-0.028	42.5	±0.2	±0.05	22.5	±0.025	6	3
460	-0.023	600	-0.028	46	±0.225	±0.06	24	±0.03	6	5³
580	-0.025	750	-0.035	60	±0.25	±0.075	30	±0.03	10	5³
650	-0.038	870	-0.05	78	±0.25	±0.1	44	±0.03	10	5³
852	-0.05	1095	-0.063	80.5	±0.3	±0.12	43.5	±0.03	12	6³
950	-0.05	1200	-0.063	86	±0.3	±0.12	46	±0.03	12	6³
1030	-0.063	1300	-0.08	92.5	±0.3	±0.15	52.5	±0.03	12	6³

For rotating inner and outer ring,measured on fitted bearing, with ideal adjacent construction.

Special design,YRT only.

By agreement only for rotating outer ring.

Dimensional tolerance				Mounting dimensions			Axial and radial runout µm
Bore		Outside diameter		H₁ mm	ΔH_1s mm	H₂ mm
d mm	Δd_s mm	D mm	ΔD_s mm	H₁ mm	ΔH_1s mm	H₂ mm
200	-0.015	300	-0.018	30	+0.04 -0.06	15	4
260	-0.018	385	-0.02	36.5	+0.05 -0.07	18.5	6
325	-0.023	450	-0.023	40	+0.06 -0.07	20	6
395	-0.023	525	-0.028	42.5	+0.06 -0.07	22.5	6
460	-0.023	600	-0.028	46	+0.07 -0.08	24	6

For rotating inner and outer ring,measured on fitted bearing, with ideal adjacent construction.

Special design:

For YRT, axial and radial runout tolerances reduced by 50%,
Additional text: axial/radial runout 50%
For YRT, loser tolerance on mounting dimensions H1 and H2. Additional text:H1 with tolerance±…; H2 with tolerance±….