Property, plant, and equipment consists of the following:


	June 30, 2021		September 30, 2020
Machinery and equipment	$	386,458	$	357,650
Rental equipment	238,953		221,953
Land and buildings	70,591		70,245
Construction in process	53,975		48,325
	749,977		698,173
Less: accumulated depreciation	(377,578)		(333,712)
	$	372,399	$	364,461

The Company entered into secured financing agreements that require providing a security interest in specified equipment. As of June 30, 2021 and September 30, 2020, the gross and net amounts of those assets are as follows:


	June 30, 2021				September 30, 2020
	Gross		Net		Gross		Net
Machinery and equipment	$	71,012	$	55,956	$	63,305	$	52,620
Construction in process	22,760		22,760		8,098		8,098
	$	93,772	$	78,716	$	71,403	$	60,718

Depreciation expense and maintenance and repairs expense for the three and nine months ended June 30, 2021 and 2020 were as follows:


	Three Months Ended June 30,				Nine Months Ended June 30,
	2021		2020		2021		2020
Depreciation expense	$	19,170	$	18,992	$	56,450	$	54,480
Maintenance and repair expense	4,603		4,601		14,565		15,915