The days of double digit Chinese economic growth are clearly over. And as policymakers look to shift from an economy based on rapid credit expansion and heavy investment in infrastructure to one based on consumer demand, miners, their industrial suppliers and some transportation firms have had to adjust.
"The steadily sliding rate of GDP growth since 2009 highlights just how tired the model for economic growth founded on capital spending has become," wrote Pictet Asia strategist Laurent Godin in a report. The Swiss asset manager predicts a more modest 6 percent to 7 percent growth from here and that weaker growth is sending reverberations through the commodities space.
Caterpillar, for one, slashed its full-year guidance as demand for its mining equipment drops off as falling China demand has forced miners to scale back new mining projects.
(Read more: Why China's economy may be heading for a crash)
"Mining has come down," Caterpillar CEO Douglas Oberhelman, told CNBC after its quarterly earnings miss. "All of our big mining customers certainly are spending less on capital."
And commodities prices, as measured by the Jefferies CRB global commodity index, have fallen nearly 6 percent this year and are down nearly 20 percent since mid-2011.
Gordon Johnson, managing director at Axiom Capital, said the issue is China.
"You're seeing a significant slowing of growth in China due to a reduction in credit," Johnson said. "That's affecting the commodities sectors and that's not reflected in stock prices or valuations."
Caterpillar hasn't been the only mining equipment supplier to feel the sting of slowing activity. Swedish rivals Atlas Copco and Sandvik highlighted falling demand from mining customers in their quarterly updates. Together both companies supply more than half the world market of underground mining equipment.
(Read more: China July flash HSBC PMI plunges to 11-month low)
"The low investment levels from miners continues to be noticeable for this part of our business," as the industry focuses on cost control and capital efficiency, Sandvik CEO Olaf Faxander said in a statement.
The slowdown has even hit the U.S. rails. Norfolk Southern CEO Wick Moorman told CNBC, "Our export coal franchise, which is aimed at the metallurgical markets, has probably suffered a little more than some of the other franchises."
He attributed it to slack demand from China, Australia's improved competitive position as the Australian dollar weakens and a struggling European economy.
"Global conditions are really what influence the price of metallurgical coal worldwide," the Norfolk Southern CEO said. "It's something that will take a while to work through, and it's something that we'll work through, as well."
Some analysts are optimistic that a bottom in the mining cycle is coming.
JPMorgan industrials analyst Ann Duignan anticipates the global macro data to stabilize, particularly as Europe starts to turn the corner. That should improve sentiment toward Caterpillar in particular, she notes.
"Going forward we think that as (the global economy) gets better, sentiment on Caterpillar's stock is better, and so we are a buyer," she said.
Caterpillar's CEO also sees an eventual recovery in mining. "Seven billion people on the planet, going to nine, [and] rising living standards around the world require minerals and energy—and that's mining," Oberhelman said.
Others caution that the mining downturn may prove nastier than the optimists anticipate, particularly as China tries to rebalance its economy.
At CNBC's Delivering Alpha conference earlier this month, Jim Chanos, the founder and managing partner of Kynikos Associates, laid out his short-thesis on Caterpillar predicated on a China slowdown.
(Read more: Jim Chanos slams Caterpillar)
"The bulls expect a capex decline in mining. But here's the problem: they expect it to decline slowly," Chanos told attendees.
Chanos pointed out that mining equipment spending was far higher than the historical average, driven in large part by the Chinese real estate bubble. The Chinese slowdown and the end of the global commodities supercycle will drive spending back down toward historical levels.
With the global economy still slowing, "the demand for metals will be low and falling, and the prices will be high and falling for some considerable time," Roger Nightingale, strategist at RDN Associates, told CNBC.
And that could mean more pain for miners and their industrial suppliers.