There were four utensils that were kept inside the Mishkan – the Shulchan, the Aron, the Mizbeach, and the Menora – the Table, the Ark, the Altar, and the Menora.
Regarding the Aron:
וְצִפִּיתָ אֹתוֹ זָהָב טָהוֹר מִבַּיִת וּמִחוּץ תְּצַפֶּנּוּ וְעָשִׂיתָ עָלָיו זֵר זָהָב סָבִיב – And you shall overlay it with pure gold; from inside and from outside you shall overlay it, and you shall make upon it a golden crown all around. (25:11)
Regarding the Shulchan:
וְצִפִּיתָ אֹתוֹ זָהָב טָהוֹר וְעָשִׂיתָ לּוֹ זֵר זָהָב סָבִיב – And you shall overlay it with pure gold, and you shall make for it a golden crown all around. (25:24)
Regarding the Mizbeach:
וְצִפִּיתָ אֹתוֹ זָהָב טָהוֹר אֶת גַּגּוֹ וְאֶת קִירֹתָיו סָבִיב וְאֶת קַרְנֹתָיו וְעָשִׂיתָ לּוֹ זֵר זָהָב סָבִיב – You shall overlay it with pure gold, its top, its walls all around, and its horns; and you shall make for it a golden crown all around. (30:3)
The Aron, Shulchan, and Mizbeach all had “crowns”, a gold design that bordered their edges, whereas the Menora is the odd one out, it had no crown. What is the cause of this discrepancy?
The Mishna in Avos 4:17 says רבי שמעון אומר, שלושה כתרים הן–כתר תורה, וכתר כהונה, וכתר מלכות; וכתר שם טוב, עולה על גביהן – R’ Shimon said, “There are three crowns – the crown of Torah, the crown of Kehuna (priesthood), and the crown of royalty – but the crown of a good name is better than all.”
The Aron represents the crown of Torah, as that was where the actual physical Torah was kept. The Mizbeach represents the crown of Kehuna, as the Avoda was the Kohanim’s job. The Shulchan represents the crown of royalty, as a table represents prestige and prosperity. But what is the crown of a good name, the כתר שם טוב, and why is it better than the other three?
And if it were an actual crown (to the degree the others are), why didn’t R’ Shimon say “There are four crowns” instead of three?
Koheles 7:1 teaches that טוֹב שֵׁם, מִשֶּׁמֶן טוֹב – A good name is more precious than good oil. The Shem Mi’Shmuel notes that the comparison indicates their similar operations; the nature of oil is to diffuse and spread out, which is exactly what a good name does.
The Menora’s function was lights fuelled by oil – by it’s very nature it must diffuse. The Menora could not have a crown, as a crown’s power and sphere of influence are confined to within the crown’s empire, and if it were to have a crown, it would limit the function the Menora served – to show the “light” of Torah and Judaism.
This is what R’ Shimon actually said too – the כתר שם טוב is not an actual crown – it diffuses, and spreads further than the three crowns. Like the Menora, a crown would inhibit it.