Maximum Load Transmitted by a Gear Based on Wear Strength and Using the Buckingham Formula The pinion of Example 11.6 is to be mated with a gear. Determine a. The allowable load for wear for the gearset using the Buckingham formula b. The maximum load that can be transmitted Given: Np = 25,

Question

Maximum Load Transmitted by a Gear Based on Wear Strength and Using the Buckingham Formula

The pinion of Example 11.6 is to be mated with a gear. Determine

a. The allowable load for wear for the gearset using the Buckingham formula

b. The maximum load that can be transmitted

Given: [latex]N_{p}[/latex] = 25, [latex]d_{p}[/latex] = 50mm, [latex]b[/latex] = 45mm, [latex]N_{g}[/latex] = 60.

Design Decision: The mating gear is made of 60-tooth cast iron.

Accepted Answer

a. Using Equation 11.40,

[latex] Q=\frac{2 N_g}{N_p+N_g}=\frac{120}{85}=\frac{24}{17} [/latex]

By Table 11.9,

[latex]K[/latex] = 1.014 MPa for 200 Bhn

Applying Equation 11.38,

[latex] F_w=d_p b Q K=(50)(45)\left(\frac{24}{17} ight)(1.014)=3.221 kN [/latex]

b. The dynamic load, from Example 11.6, is 1.77[latex]F_{t}[/latex] The wear-limiting value of the transmitted load, using Equation 11.41, is then

[latex] F_w \geq F_d [/latex] (11.41)

[latex] 3.221=1.77 F_t \quad ext { or } \quad F_t=1.82 kN [/latex]

Table 11.9 Surface Endurance Limit [latex]S_{e}[/latex] and Wear Load Factor [latex]K[/latex] for Use in the Buckingham Equation
			[latex]K[/latex]
	[latex]S_{e}[/latex]		[latex] \phi=20^{\circ} [/latex]		[latex] \phi=25^{\circ} [/latex]
Materials in Pinion and Gear	ksi	(MPa)	psi	(MPa)	psi	(MPa)
Both steel gears, with average
Bhn of pinion and gear
150	50	(345)	41	(0.283)	51	(0.352)
200	70	(483)	79	(0.545)	98	(0.676)
250	90	(621)	131	(0.903)	162	(1.117)
300	110	(758)	196	(1.352)	242	(1.669)
350	130	(896)	270	(1.862)	333	(2.297)
400	150	(1034)	366	(2.524)	453	(3.124)
Steel (150 Bhn) and cast iron	50	(354)	60	(0.414)	74	(0.510)
Steel (200 Bhn) and cast iron	70	(483)	119	(0.821)	147	(1.014)
Steel (250 Bhn) and cast iron	90	(621)	196	(1.352)	242	(1.669)
Steel (150 Bhn) and phosphor bronze	59	(407)	62	(0.428)	77	(0.531)
Steel (200 Bhn) and phosphor bronze	65	(448)	100	(0.690)	123	(0.848)
Steel (250 Bhn) and phosphor bronze	85	(586)	184	(1.269)	228	(1.572)
Cast iron and cast iron	90	(621)	264	(1.821)	327	(2.555)
Cast iron and phosphor bronze	83	(572)	234	(1.614)	288	(1.986)

Question 11.8: Maximum Load Transmitted by a Gear Based on Wear Strength an...